<?xml version="1.0" encoding="US-ASCII"?>
<!--XBRL Document Created with Wdesk from Workiva-->
<!-- -->
<link:linkbase xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BasisOfPresentationUnaudited" xlink:href="noc-20190630.xsd#BasisOfPresentationUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails1" xlink:href="noc-20190630.xsd#BasisOfPresentationUnauditedDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails2" xlink:href="noc-20190630.xsd#BasisOfPresentationUnauditedDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails3" xlink:href="noc-20190630.xsd#BasisOfPresentationUnauditedDetails3" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails4" xlink:href="noc-20190630.xsd#BasisOfPresentationUnauditedDetails4" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedTables" xlink:href="noc-20190630.xsd#BasisOfPresentationUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedBusinessAcquisitionUnaudited" xlink:href="noc-20190630.xsd#BusinessAcquisitionUnauditedBusinessAcquisitionUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedBusinessAcquisitionUnauditedTables" xlink:href="noc-20190630.xsd#BusinessAcquisitionUnauditedBusinessAcquisitionUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedDetails1" xlink:href="noc-20190630.xsd#BusinessAcquisitionUnauditedDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedDetails2" xlink:href="noc-20190630.xsd#BusinessAcquisitionUnauditedDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedDetails3" xlink:href="noc-20190630.xsd#BusinessAcquisitionUnauditedDetails3" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CommitmentsAndContingenciesUnaudited" xlink:href="noc-20190630.xsd#CommitmentsAndContingenciesUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CommitmentsAndContingenciesUnauditedDetails" xlink:href="noc-20190630.xsd#CommitmentsAndContingenciesUnauditedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CommitmentsAndContingenciesUnauditedTables" xlink:href="noc-20190630.xsd#CommitmentsAndContingenciesUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:href="noc-20190630.xsd#CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfChangesInShareholdersEquityUnaudited" xlink:href="noc-20190630.xsd#CondensedConsolidatedStatementsOfChangesInShareholdersEquityUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfEarningsAndComprehensiveIncomeUnaudited" xlink:href="noc-20190630.xsd#CondensedConsolidatedStatementsOfEarningsAndComprehensiveIncomeUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfFinancialPositionUnaudited" xlink:href="noc-20190630.xsd#CondensedConsolidatedStatementsOfFinancialPositionUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfFinancialPositionUnauditedParentheticals" xlink:href="noc-20190630.xsd#CondensedConsolidatedStatementsOfFinancialPositionUnauditedParentheticals" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/DocumentAndEntityInformationDocument" xlink:href="noc-20190630.xsd#DocumentAndEntityInformationDocument" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnaudited" xlink:href="noc-20190630.xsd#EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedDetails1" xlink:href="noc-20190630.xsd#EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedDetails2" xlink:href="noc-20190630.xsd#EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedTables" xlink:href="noc-20190630.xsd#EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnaudited" xlink:href="noc-20190630.xsd#FairValueOfFinancialInstrumentsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedDetails1" xlink:href="noc-20190630.xsd#FairValueOfFinancialInstrumentsUnauditedDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedDetails2" xlink:href="noc-20190630.xsd#FairValueOfFinancialInstrumentsUnauditedDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedFairValueOfFinancialInstrumentsUnauditedDetails3" xlink:href="noc-20190630.xsd#FairValueOfFinancialInstrumentsUnauditedFairValueOfFinancialInstrumentsUnauditedDetails3" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedTables" xlink:href="noc-20190630.xsd#FairValueOfFinancialInstrumentsUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/IncomeTaxesUnaudited" xlink:href="noc-20190630.xsd#IncomeTaxesUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/IncomeTaxesUnauditedDetails1" xlink:href="noc-20190630.xsd#IncomeTaxesUnauditedDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/IncomeTaxesUnauditedDetails2" xlink:href="noc-20190630.xsd#IncomeTaxesUnauditedDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/IncomeTaxesUnauditedTables" xlink:href="noc-20190630.xsd#IncomeTaxesUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/InvestigationsClaimsAndLitigationUnaudited" xlink:href="noc-20190630.xsd#InvestigationsClaimsAndLitigationUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/InvestigationsClaimsAndLitigationUnauditedDetails" xlink:href="noc-20190630.xsd#InvestigationsClaimsAndLitigationUnauditedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/LeasesUnauditedFutureMinimumLeasePaymentsUnder840Details" xlink:href="noc-20190630.xsd#LeasesUnauditedFutureMinimumLeasePaymentsUnder840Details" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/LeasesUnauditedLeaseBalanceSheetDetails" xlink:href="noc-20190630.xsd#LeasesUnauditedLeaseBalanceSheetDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/LeasesUnauditedLeaseMaturitiesDetails" xlink:href="noc-20190630.xsd#LeasesUnauditedLeaseMaturitiesDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/LeasesUnauditedLeaseOtherSupplementalInformationDetails" xlink:href="noc-20190630.xsd#LeasesUnauditedLeaseOtherSupplementalInformationDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/LeasesUnauditedLeasesTables" xlink:href="noc-20190630.xsd#LeasesUnauditedLeasesTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/LeasesUnauditedNotes" xlink:href="noc-20190630.xsd#LeasesUnauditedNotes" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/LeasesUnauditedTotalLeaseCostDetails" xlink:href="noc-20190630.xsd#LeasesUnauditedTotalLeaseCostDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/RetirementBenefitsUnaudited" xlink:href="noc-20190630.xsd#RetirementBenefitsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/RetirementBenefitsUnauditedDetails" xlink:href="noc-20190630.xsd#RetirementBenefitsUnauditedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/RetirementBenefitsUnauditedTables" xlink:href="noc-20190630.xsd#RetirementBenefitsUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/SegmentInformationUnaudited" xlink:href="noc-20190630.xsd#SegmentInformationUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails1" xlink:href="noc-20190630.xsd#SegmentInformationUnauditedDetails1" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails2" xlink:href="noc-20190630.xsd#SegmentInformationUnauditedDetails2" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails3" xlink:href="noc-20190630.xsd#SegmentInformationUnauditedDetails3" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails4" xlink:href="noc-20190630.xsd#SegmentInformationUnauditedDetails4" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/SegmentInformationUnauditedTables" xlink:href="noc-20190630.xsd#SegmentInformationUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/StockCompensationPlansAndOtherCompensationArrangementsUnaudited" xlink:href="noc-20190630.xsd#StockCompensationPlansAndOtherCompensationArrangementsUnaudited" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/StockCompensationPlansAndOtherCompensationArrangementsUnauditedDetails" xlink:href="noc-20190630.xsd#StockCompensationPlansAndOtherCompensationArrangementsUnauditedDetails" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/StockCompensationPlansAndOtherCompensationArrangementsUnauditedTables" xlink:href="noc-20190630.xsd#StockCompensationPlansAndOtherCompensationArrangementsUnauditedTables" xlink:type="simple" />
  <link:roleRef roleURI="http://www.northropgrumman.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:href="noc-20190630.xsd#SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" xlink:type="simple" />
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" xlink:type="simple" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BasisOfPresentationUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ChangeInAccountingEstimateLineItems" xlink:label="loc_us-gaap_ChangeInAccountingEstimateLineItems_C55F9BFE906F4D10E546D2E95DF9248D" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfChangeInAccountingEstimateTable" xlink:label="loc_us-gaap_ScheduleOfChangeInAccountingEstimateTable_37D6B877B0D25D5A011DD2E95DF23FF7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_C55F9BFE906F4D10E546D2E95DF9248D" xlink:to="loc_us-gaap_ScheduleOfChangeInAccountingEstimateTable_37D6B877B0D25D5A011DD2E95DF23FF7" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_A756922A58814DBA4A46D2E95DF7DAC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfChangeInAccountingEstimateTable_37D6B877B0D25D5A011DD2E95DF23FF7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_A756922A58814DBA4A46D2E95DF7DAC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_2F1CE0B1BEB7B2C0A1E4D2E95DF8FA1B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_A756922A58814DBA4A46D2E95DF7DAC1" xlink:to="loc_us-gaap_SegmentDomain_2F1CE0B1BEB7B2C0A1E4D2E95DF8FA1B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_2F1CE0B1BEB7B2C0A1E4D2E95DF8FA1B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_A756922A58814DBA4A46D2E95DF7DAC1" xlink:to="loc_us-gaap_SegmentDomain_2F1CE0B1BEB7B2C0A1E4D2E95DF8FA1B" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AerospaceSystemsMember" xlink:label="loc_noc_AerospaceSystemsMember_2E4A6BE65AC763897C84D2E95DF8F8D1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_2F1CE0B1BEB7B2C0A1E4D2E95DF8FA1B" xlink:to="loc_noc_AerospaceSystemsMember_2E4A6BE65AC763897C84D2E95DF8F8D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ChangeInAccountingEstimateByTypeAxis" xlink:label="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_49D45C54694DF86B2068D2E95DF88493" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfChangeInAccountingEstimateTable_37D6B877B0D25D5A011DD2E95DF23FF7" xlink:to="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_49D45C54694DF86B2068D2E95DF88493" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_0318B86D244E0E9E887ED2E95DF93249_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_49D45C54694DF86B2068D2E95DF88493" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_0318B86D244E0E9E887ED2E95DF93249_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ChangeInAccountingEstimateTypeDomain" xlink:label="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_0318B86D244E0E9E887ED2E95DF93249" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ChangeInAccountingEstimateByTypeAxis_49D45C54694DF86B2068D2E95DF88493" xlink:to="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_0318B86D244E0E9E887ED2E95DF93249" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractsAccountedForUnderPercentageOfCompletionMember" xlink:label="loc_us-gaap_ContractsAccountedForUnderPercentageOfCompletionMember_E37A01CC5D38F251EE56D2E95DF9FED9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateTypeDomain_0318B86D244E0E9E887ED2E95DF93249" xlink:to="loc_us-gaap_ContractsAccountedForUnderPercentageOfCompletionMember_E37A01CC5D38F251EE56D2E95DF9FED9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_9E0D710FE97BAFC71436D2E95DF9160D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_C55F9BFE906F4D10E546D2E95DF9248D" xlink:to="loc_us-gaap_OperatingIncomeLoss_9E0D710FE97BAFC71436D2E95DF9160D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_4CC08BAC7F3B1DEEAA19D2E95DFA16D1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_C55F9BFE906F4D10E546D2E95DF9248D" xlink:to="loc_us-gaap_NetIncomeLoss_4CC08BAC7F3B1DEEAA19D2E95DFA16D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EarningsPerShareDiluted" xlink:label="loc_us-gaap_EarningsPerShareDiluted_C31172AE4E597913AB0FD2E95DFAFA17" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_C55F9BFE906F4D10E546D2E95DF9248D" xlink:to="loc_us-gaap_EarningsPerShareDiluted_C31172AE4E597913AB0FD2E95DFAFA17" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod" xlink:label="loc_us-gaap_ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod_FA27854F5A7DBF89CCADD2E95DFA89CC" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ChangeInAccountingEstimateLineItems_C55F9BFE906F4D10E546D2E95DF9248D" xlink:to="loc_us-gaap_ContractWithCustomerPerformanceObligationSatisfiedInPreviousPeriod_FA27854F5A7DBF89CCADD2E95DFA89CC" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails2" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails3" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedDetails4" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BasisOfPresentationUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedBusinessAcquisitionUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedBusinessAcquisitionUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8748958845F55387C33BE3FEE840BCCD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8748958845F55387C33BE3FEE840BCCD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_1AD42EEAC16A57940EDDE3FEE840EDF9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8748958845F55387C33BE3FEE840BCCD" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_1AD42EEAC16A57940EDDE3FEE840EDF9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2CFD1B7C6FE5F0221AE9E3FEE840009C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1AD42EEAC16A57940EDDE3FEE840EDF9" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2CFD1B7C6FE5F0221AE9E3FEE840009C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2CFD1B7C6FE5F0221AE9E3FEE840009C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_1AD42EEAC16A57940EDDE3FEE840EDF9" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2CFD1B7C6FE5F0221AE9E3FEE840009C" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_OrbitalATKMember" xlink:label="loc_noc_OrbitalATKMember_CFF09BF075BC0AB1E7EEE3FEE8400DD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_2CFD1B7C6FE5F0221AE9E3FEE840009C" xlink:to="loc_noc_OrbitalATKMember_CFF09BF075BC0AB1E7EEE3FEE8400DD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationAxis" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_3AF419E458C30212F363E3FEE8409256" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8748958845F55387C33BE3FEE840BCCD" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_3AF419E458C30212F363E3FEE8409256" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_B2DAAAFBFC093CFA355EE3FEE840BD34_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_3AF419E458C30212F363E3FEE8409256" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_B2DAAAFBFC093CFA355EE3FEE840BD34_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncomeStatementLocationDomain" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_B2DAAAFBFC093CFA355EE3FEE840BD34" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_3AF419E458C30212F363E3FEE8409256" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_B2DAAAFBFC093CFA355EE3FEE840BD34" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_OwnershipAxis" xlink:label="loc_srt_OwnershipAxis_AC99473ADC47488FEA42E3FEE84077E6" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8748958845F55387C33BE3FEE840BCCD" xlink:to="loc_srt_OwnershipAxis_AC99473ADC47488FEA42E3FEE84077E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_OwnershipDomain" xlink:label="loc_srt_OwnershipDomain_0F901B74860879F33D07E3FEE840E144_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_AC99473ADC47488FEA42E3FEE84077E6" xlink:to="loc_srt_OwnershipDomain_0F901B74860879F33D07E3FEE840E144_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_OwnershipDomain" xlink:label="loc_srt_OwnershipDomain_0F901B74860879F33D07E3FEE840E144" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_AC99473ADC47488FEA42E3FEE84077E6" xlink:to="loc_srt_OwnershipDomain_0F901B74860879F33D07E3FEE840E144" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaap_StatementClassOfStockAxis_15F51546925730175596E3FEE8407A5D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8748958845F55387C33BE3FEE840BCCD" xlink:to="loc_us-gaap_StatementClassOfStockAxis_15F51546925730175596E3FEE8407A5D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_A994656255B22AE6AAD6E3FEE850EF59_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementClassOfStockAxis_15F51546925730175596E3FEE8407A5D" xlink:to="loc_us-gaap_ClassOfStockDomain_A994656255B22AE6AAD6E3FEE850EF59_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaap_ClassOfStockDomain_A994656255B22AE6AAD6E3FEE850EF59" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementClassOfStockAxis_15F51546925730175596E3FEE8407A5D" xlink:to="loc_us-gaap_ClassOfStockDomain_A994656255B22AE6AAD6E3FEE850EF59" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles_55B41D2777F3BA44416DE3FEE8503468" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentIntangibles_55B41D2777F3BA44416DE3FEE8503468" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOthercurrentliabilities" xlink:label="loc_noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOthercurrentliabilities_C5B9CE0F1D4D22DEBF68E3FEE8509AB3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOthercurrentliabilities_C5B9CE0F1D4D22DEBF68E3FEE8509AB3" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPensionandotherpostretirementbenefitplanliabilities" xlink:label="loc_noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPensionandotherpostretirementbenefitplanliabilities_96F43496600F358738B6E3FEE850A68B" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPensionandotherpostretirementbenefitplanliabilities_96F43496600F358738B6E3FEE850A68B" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationProvisionalInitialAccountingIncompleteAdjustmentsOtherNonCurrentLiabilities" xlink:label="loc_noc_BusinessCombinationProvisionalInitialAccountingIncompleteAdjustmentsOtherNonCurrentLiabilities_09FAAA167A5D965EA165E3FEE8507F73" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationProvisionalInitialAccountingIncompleteAdjustmentsOtherNonCurrentLiabilities_09FAAA167A5D965EA165E3FEE8507F73" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationProvisionalInitialAccountingIncompleteAdjustmentsOtherCurrentAssets" xlink:label="loc_noc_BusinessCombinationProvisionalInitialAccountingIncompleteAdjustmentsOtherCurrentAssets_73B8AF4892F33DC4BCEBE400D6FF7049" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationProvisionalInitialAccountingIncompleteAdjustmentsOtherCurrentAssets_73B8AF4892F33DC4BCEBE400D6FF7049" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentGoodwill" xlink:label="loc_noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentGoodwill_18364F2D8A2FB391E141E3FEE850EFE3" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentGoodwill_18364F2D8A2FB391E141E3FEE850EFE3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_D46D35DF93A75123D45DE3FEE850A5B7" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCashAndEquivalents_D46D35DF93A75123D45DE3FEE850A5B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_4DFA2384BEA2163F2064E3FEE850D2FB" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_4DFA2384BEA2163F2064E3FEE850D2FB" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsUnbilledReceivables" xlink:label="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsUnbilledReceivables_01AE586F823399304190E3FEE850CB78" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentAssetsUnbilledReceivables_01AE586F823399304190E3FEE850CB78" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_0788BE40A30F0D864056E3FEE850A7D3" xlink:type="locator" />
    <link:definitionArc order="10" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedInventory_0788BE40A30F0D864056E3FEE850A7D3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_D65476D9CE51C94E05C5E3FEE8501F33" xlink:type="locator" />
    <link:definitionArc order="11" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsPrepaidExpenseAndOtherAssets_D65476D9CE51C94E05C5E3FEE8501F33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_BEAC847948146FB09877E3FEE8507492" xlink:type="locator" />
    <link:definitionArc order="12" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_BEAC847948146FB09877E3FEE8507492" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaap_Goodwill_33C892FC4D2043877CD7E3FEE850B710" xlink:type="locator" />
    <link:definitionArc order="13" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_Goodwill_33C892FC4D2043877CD7E3FEE850B710" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_0A7A28AD2466935E879BE3FEE8500737" xlink:type="locator" />
    <link:definitionArc order="14" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_0A7A28AD2466935E879BE3FEE8500737" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_63BF354B5C3D15C216A5E3FEE850840C" xlink:type="locator" />
    <link:definitionArc order="15" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedOtherNoncurrentAssets_63BF354B5C3D15C216A5E3FEE850840C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_2B76C212E4B87CD5B816E3FEE85082CC" xlink:type="locator" />
    <link:definitionArc order="16" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAssets_2B76C212E4B87CD5B816E3FEE85082CC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_B8B3370F16BDBCB6BC63E3FEE850CF50" xlink:type="locator" />
    <link:definitionArc order="17" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_B8B3370F16BDBCB6BC63E3FEE850CF50" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesEmployeerelatedliabilities" xlink:label="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesEmployeerelatedliabilities_104F64B0C98D2B317192E3FEE8509BA1" xlink:type="locator" />
    <link:definitionArc order="18" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesEmployeerelatedliabilities_104F64B0C98D2B317192E3FEE8509BA1" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesCustomerAdvances" xlink:label="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesCustomerAdvances_C76ED610C1C21C25C3C4E3FEE85068A7" xlink:type="locator" />
    <link:definitionArc order="19" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesCustomerAdvances_C76ED610C1C21C25C3C4E3FEE85068A7" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesBelowMarketContracts" xlink:label="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesBelowMarketContracts_C4F6D3AEA1CDC2BE8CBBE3FEE850EE0E" xlink:type="locator" />
    <link:definitionArc order="20" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedCurrentLiabilitiesBelowMarketContracts_C4F6D3AEA1CDC2BE8CBBE3FEE850EE0E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_751242A6B61707215A99E3FEE85077D7" xlink:type="locator" />
    <link:definitionArc order="21" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesOther_751242A6B61707215A99E3FEE85077D7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_67514C6A0378A3CFFB36E3FEE8505AA8" xlink:type="locator" />
    <link:definitionArc order="22" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_67514C6A0378A3CFFB36E3FEE8505AA8" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNonCurrentLiabilitiesDefinedBenefitPlanLiability" xlink:label="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNonCurrentLiabilitiesDefinedBenefitPlanLiability_D1E9153B049FC1B525ECE3FEE85056B9" xlink:type="locator" />
    <link:definitionArc order="23" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_noc_BusinessCombinationRecognizedIdentifiableAssetsAcquiredandLiabilitiesAssumedNonCurrentLiabilitiesDefinedBenefitPlanLiability_D1E9153B049FC1B525ECE3FEE85056B9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_A30DB2494BABC9BD3197E3FEE850FAA1" xlink:type="locator" />
    <link:definitionArc order="24" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_A30DB2494BABC9BD3197E3FEE850FAA1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_24E36D3523C7478692FFE3FEE8507B89" xlink:type="locator" />
    <link:definitionArc order="25" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_24E36D3523C7478692FFE3FEE8507B89" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_7999E85C17E7E3716B06E3FEE850DA7F" xlink:type="locator" />
    <link:definitionArc order="26" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedLiabilities_7999E85C17E7E3716B06E3FEE850DA7F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_CC99D9B2AED895C4EE3CE3FEE8507FE3" xlink:type="locator" />
    <link:definitionArc order="27" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_9A4FC1ABCEADA2620A89E3FEE850DB09" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNet_CC99D9B2AED895C4EE3CE3FEE8507FE3" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedDetails2" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_54F2327FB86D1D046BEED2E95D750125" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_78D99108B7A457586582D2E95D73A634" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_54F2327FB86D1D046BEED2E95D750125" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_78D99108B7A457586582D2E95D73A634" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6F87C01B8FBD1D706EBCD2E95D73FA47" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_78D99108B7A457586582D2E95D73A634" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6F87C01B8FBD1D706EBCD2E95D73FA47" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C82417841AF11DE8EB7FD2E95D73FE26_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6F87C01B8FBD1D706EBCD2E95D73FA47" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C82417841AF11DE8EB7FD2E95D73FE26_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C82417841AF11DE8EB7FD2E95D73FE26" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_6F87C01B8FBD1D706EBCD2E95D73FA47" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C82417841AF11DE8EB7FD2E95D73FE26" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CustomerContractsMember" xlink:label="loc_us-gaap_CustomerContractsMember_D896927C0E945D877566D2E95D73C6B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C82417841AF11DE8EB7FD2E95D73FE26" xlink:to="loc_us-gaap_CustomerContractsMember_D896927C0E945D877566D2E95D73C6B2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CustomerRelationshipsMember" xlink:label="loc_us-gaap_CustomerRelationshipsMember_9DA3ECBF00800626B7D4D2E95D74D785" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_C82417841AF11DE8EB7FD2E95D73FE26" xlink:to="loc_us-gaap_CustomerRelationshipsMember_9DA3ECBF00800626B7D4D2E95D74D785" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_52A83F3102A4DC7D5531D2E95D74E884" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_78D99108B7A457586582D2E95D73A634" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_52A83F3102A4DC7D5531D2E95D74E884" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5B064728180AAAAC7475D2E95D7410E8_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_52A83F3102A4DC7D5531D2E95D74E884" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5B064728180AAAAC7475D2E95D7410E8_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5B064728180AAAAC7475D2E95D7410E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_52A83F3102A4DC7D5531D2E95D74E884" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5B064728180AAAAC7475D2E95D7410E8" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_OrbitalATKMember" xlink:label="loc_noc_OrbitalATKMember_868A3AF6FD1C5AD7C147D2E95D74738B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5B064728180AAAAC7475D2E95D7410E8" xlink:to="loc_noc_OrbitalATKMember_868A3AF6FD1C5AD7C147D2E95D74738B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_DFE2B4C5E816B3B3DE43D2E95D75BF70" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_54F2327FB86D1D046BEED2E95D750125" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_DFE2B4C5E816B3B3DE43D2E95D75BF70" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9688934EAFA6DFA2E1B2D2E95D7522B9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_54F2327FB86D1D046BEED2E95D750125" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_9688934EAFA6DFA2E1B2D2E95D7522B9" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/BusinessAcquisitionUnauditedDetails3" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_743232694559424BD9DED2E95D5FC7CB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_743232694559424BD9DED2E95D5FC7CB" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_083CA00011437C55FE28D2E95D5F432E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_743232694559424BD9DED2E95D5FC7CB" xlink:to="loc_srt_ConsolidationItemsAxis_083CA00011437C55FE28D2E95D5F432E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_E3D5EF69FEBF32BBB480D2E95D60CD04_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_083CA00011437C55FE28D2E95D5F432E" xlink:to="loc_srt_ConsolidationItemsDomain_E3D5EF69FEBF32BBB480D2E95D60CD04_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_E3D5EF69FEBF32BBB480D2E95D60CD04" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_083CA00011437C55FE28D2E95D5F432E" xlink:to="loc_srt_ConsolidationItemsDomain_E3D5EF69FEBF32BBB480D2E95D60CD04" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_A5137410D98F735E4661D2E95D60F44D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_743232694559424BD9DED2E95D5FC7CB" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_A5137410D98F735E4661D2E95D60F44D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_D0C4FBDA6B6341CFE8E6D2E95D600192_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_A5137410D98F735E4661D2E95D60F44D" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_D0C4FBDA6B6341CFE8E6D2E95D600192_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_D0C4FBDA6B6341CFE8E6D2E95D600192" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_A5137410D98F735E4661D2E95D60F44D" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_D0C4FBDA6B6341CFE8E6D2E95D600192" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_OrbitalATKMember" xlink:label="loc_noc_OrbitalATKMember_9C4878DC61E38A996DC9D2E95D60AB4D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_D0C4FBDA6B6341CFE8E6D2E95D600192" xlink:to="loc_noc_OrbitalATKMember_9C4878DC61E38A996DC9D2E95D60AB4D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaRevenue" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_87F54ED948727704C7A6D2E95D619313" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaRevenue_87F54ED948727704C7A6D2E95D619313" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss" xlink:label="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_761E3AB72373FB2C4D4DD2E95D611CFD" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_us-gaap_BusinessAcquisitionsProFormaNetIncomeLoss_761E3AB72373FB2C4D4DD2E95D611CFD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted" xlink:label="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_E7C5499FE28B398D656FD2E95D61BC0F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_us-gaap_BusinessAcquisitionProFormaEarningsPerShareDiluted_E7C5499FE28B398D656FD2E95D61BC0F" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ProFormaAdjustmentsOrbitalATKintercompanysaleselimination" xlink:label="loc_noc_ProFormaAdjustmentsOrbitalATKintercompanysaleselimination_153FFDD08CD1ED33DAF6D2E95D619A24" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_noc_ProFormaAdjustmentsOrbitalATKintercompanysaleselimination_153FFDD08CD1ED33DAF6D2E95D619A24" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ProFormaAdjustmentsEliminationofnonrecurringtransactioncosts" xlink:label="loc_noc_ProFormaAdjustmentsEliminationofnonrecurringtransactioncosts_62E872581FB61683CA3BD2E95D626F80" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_noc_ProFormaAdjustmentsEliminationofnonrecurringtransactioncosts_62E872581FB61683CA3BD2E95D626F80" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ProFormaAdjustmentsAdditionaldepreciationexpensenetofremovalofhistoricaldepreciation" xlink:label="loc_noc_ProFormaAdjustmentsAdditionaldepreciationexpensenetofremovalofhistoricaldepreciation_D8BE34B7E158271840E0D2E95D622DB1" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_noc_ProFormaAdjustmentsAdditionaldepreciationexpensenetofremovalofhistoricaldepreciation_D8BE34B7E158271840E0D2E95D622DB1" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ProFormaAdjustmentsAdditionalamortizationexpensenetofremovalofhistoricalamortizationexpense" xlink:label="loc_noc_ProFormaAdjustmentsAdditionalamortizationexpensenetofremovalofhistoricalamortizationexpense_95395365E03C366DC58BD2E95D6247A4" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_noc_ProFormaAdjustmentsAdditionalamortizationexpensenetofremovalofhistoricalamortizationexpense_95395365E03C366DC58BD2E95D6247A4" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ProFormaAdjustmentsEliminationofOrbitalATKshistoricalamortizationofnetactuariallossesandpriorservicecreditsandrevisedpensionandotherpostretirementcosts" xlink:label="loc_noc_ProFormaAdjustmentsEliminationofOrbitalATKshistoricalamortizationofnetactuariallossesandpriorservicecreditsandrevisedpensionandotherpostretirementcosts_A866C1E428B5A11D8E35D2E95D62E03C" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_noc_ProFormaAdjustmentsEliminationofOrbitalATKshistoricalamortizationofnetactuariallossesandpriorservicecreditsandrevisedpensionandotherpostretirementcosts_A866C1E428B5A11D8E35D2E95D62E03C" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_IncomeTaxEffectsofProFormaAdjustments" xlink:label="loc_noc_IncomeTaxEffectsofProFormaAdjustments_062C1EAA0267574A967FD2E95D62EDF4" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_DF8B91347BABD985639BD2E95D6139DA" xlink:to="loc_noc_IncomeTaxEffectsofProFormaAdjustments_062C1EAA0267574A967FD2E95D62EDF4" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CommitmentsAndContingenciesUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CommitmentsAndContingenciesUnauditedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SiteContingencyLineItems" xlink:label="loc_us-gaap_SiteContingencyLineItems_FDACB4B99912FE59C3C8D2E95C97B18F" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SiteContingencyTable" xlink:label="loc_us-gaap_SiteContingencyTable_E247A0ECBE8107838EE0D2E95C937F78" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SiteContingencyLineItems_FDACB4B99912FE59C3C8D2E95C97B18F" xlink:to="loc_us-gaap_SiteContingencyTable_E247A0ECBE8107838EE0D2E95C937F78" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_FBB93C2AA4813F59EA5AD2E95C94A7FC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SiteContingencyTable_E247A0ECBE8107838EE0D2E95C937F78" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_FBB93C2AA4813F59EA5AD2E95C94A7FC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_542CAA8826413B9A0F24D2E95C944187_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_FBB93C2AA4813F59EA5AD2E95C94A7FC" xlink:to="loc_us-gaap_LossContingencyNatureDomain_542CAA8826413B9A0F24D2E95C944187_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_542CAA8826413B9A0F24D2E95C944187" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_FBB93C2AA4813F59EA5AD2E95C94A7FC" xlink:to="loc_us-gaap_LossContingencyNatureDomain_542CAA8826413B9A0F24D2E95C944187" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EnvironmentalIssueMember" xlink:label="loc_us-gaap_EnvironmentalIssueMember_63DBF09409FB877D7824D2E95C94817E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_542CAA8826413B9A0F24D2E95C944187" xlink:to="loc_us-gaap_EnvironmentalIssueMember_63DBF09409FB877D7824D2E95C94817E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_DFF39C5AB6226839111BD2E95C95F8D5" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SiteContingencyTable_E247A0ECBE8107838EE0D2E95C937F78" xlink:to="loc_srt_RangeAxis_DFF39C5AB6226839111BD2E95C95F8D5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_5A09DC98D67256B498CFD2E95C95C2A4_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_DFF39C5AB6226839111BD2E95C95F8D5" xlink:to="loc_srt_RangeMember_5A09DC98D67256B498CFD2E95C95C2A4_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_5A09DC98D67256B498CFD2E95C95C2A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_DFF39C5AB6226839111BD2E95C95F8D5" xlink:to="loc_srt_RangeMember_5A09DC98D67256B498CFD2E95C95C2A4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_5B8E2A217B67FCB83067D2E95C95E6D2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5A09DC98D67256B498CFD2E95C95C2A4" xlink:to="loc_srt_MaximumMember_5B8E2A217B67FCB83067D2E95C95E6D2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_40471BA4210AF9B36F29D2E95C95FC03" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_5A09DC98D67256B498CFD2E95C95C2A4" xlink:to="loc_srt_MinimumMember_40471BA4210AF9B36F29D2E95C95FC03" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationAxis" xlink:label="loc_us-gaap_BalanceSheetLocationAxis_2B0708D7D760E0E5B0E5D2E95C96C284" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SiteContingencyTable_E247A0ECBE8107838EE0D2E95C937F78" xlink:to="loc_us-gaap_BalanceSheetLocationAxis_2B0708D7D760E0E5B0E5D2E95C96C284" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2B0708D7D760E0E5B0E5D2E95C96C284" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BalanceSheetLocationDomain" xlink:label="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BalanceSheetLocationAxis_2B0708D7D760E0E5B0E5D2E95C96C284" xlink:to="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherCurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherCurrentLiabilitiesMember_36736E3B622A2F3ED67AD2E95C961C9E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724" xlink:to="loc_us-gaap_OtherCurrentLiabilitiesMember_36736E3B622A2F3ED67AD2E95C961C9E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNoncurrentLiabilitiesMember" xlink:label="loc_us-gaap_OtherNoncurrentLiabilitiesMember_2EC428BFE901E40FD4BCD2E95C97F748" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724" xlink:to="loc_us-gaap_OtherNoncurrentLiabilitiesMember_2EC428BFE901E40FD4BCD2E95C97F748" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherCurrentAssetsMember" xlink:label="loc_us-gaap_OtherCurrentAssetsMember_3165C13BFC39E5FF0796D2E95C97BB0C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724" xlink:to="loc_us-gaap_OtherCurrentAssetsMember_3165C13BFC39E5FF0796D2E95C97BB0C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherNoncurrentAssetsMember" xlink:label="loc_us-gaap_OtherNoncurrentAssetsMember_B56486F06AF5E64926F8D2E95C97EF82" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BalanceSheetLocationDomain_29DC2143764754860D76D2E95C962724" xlink:to="loc_us-gaap_OtherNoncurrentAssetsMember_B56486F06AF5E64926F8D2E95C97EF82" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_657EC274A0FD0D573E5AD2E95C97254A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_FDACB4B99912FE59C3C8D2E95C97B18F" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_657EC274A0FD0D573E5AD2E95C97254A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccrualForEnvironmentalLossContingencies" xlink:label="loc_us-gaap_AccrualForEnvironmentalLossContingencies_138221F0B2527DD10CA7D2E95C97B1FA" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_FDACB4B99912FE59C3C8D2E95C97B18F" xlink:to="loc_us-gaap_AccrualForEnvironmentalLossContingencies_138221F0B2527DD10CA7D2E95C97B1FA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RecordedThirdPartyEnvironmentalRecoveriesAmount" xlink:label="loc_us-gaap_RecordedThirdPartyEnvironmentalRecoveriesAmount_4A85AB0C89446E3A6B6AD2E95C980ABE" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SiteContingencyLineItems_FDACB4B99912FE59C3C8D2E95C97B18F" xlink:to="loc_us-gaap_RecordedThirdPartyEnvironmentalRecoveriesAmount_4A85AB0C89446E3A6B6AD2E95C980ABE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityLineItems" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityTable" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_A1CA93D3D55A9D8A666CD2E95C99EB97" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_A1CA93D3D55A9D8A666CD2E95C99EB97" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommercialPaperMember" xlink:label="loc_us-gaap_CommercialPaperMember_B97929C47DA690A71754D2E95C998ABF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_A1CA93D3D55A9D8A666CD2E95C99EB97" xlink:to="loc_us-gaap_CommercialPaperMember_B97929C47DA690A71754D2E95C998ABF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_02DCF379C2BD3D4ADF9DD2E95C99C278" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_A1CA93D3D55A9D8A666CD2E95C99EB97" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_02DCF379C2BD3D4ADF9DD2E95C99C278" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommercialPaperMember" xlink:label="loc_us-gaap_CommercialPaperMember_B97929C47DA690A71754D2E95C998ABF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_02DCF379C2BD3D4ADF9DD2E95C99C278" xlink:to="loc_us-gaap_CommercialPaperMember_B97929C47DA690A71754D2E95C998ABF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_EC1589FBBDE16523BA14D2E95C9A2D08" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_EC1589FBBDE16523BA14D2E95C9A2D08" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_C86C2D246AEFB4FD9B80D2E95C9AD32E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_EC1589FBBDE16523BA14D2E95C9A2D08" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_C86C2D246AEFB4FD9B80D2E95C9AD32E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_C86C2D246AEFB4FD9B80D2E95C9AD32E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_EC1589FBBDE16523BA14D2E95C9A2D08" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_C86C2D246AEFB4FD9B80D2E95C9AD32E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_FBCAC9543825384643A9D2E95C9A70E2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_FBCAC9543825384643A9D2E95C9A70E2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FD92AF6E4238E4A93C83D2E95C9A1963_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_FBCAC9543825384643A9D2E95C9A70E2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FD92AF6E4238E4A93C83D2E95C9A1963_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FD92AF6E4238E4A93C83D2E95C9A1963" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_FBCAC9543825384643A9D2E95C9A70E2" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FD92AF6E4238E4A93C83D2E95C9A1963" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_OrbitalATKMember" xlink:label="loc_noc_OrbitalATKMember_E57E498DB50E440F83AAD2E95C9B7BBC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_FD92AF6E4238E4A93C83D2E95C9A1963" xlink:to="loc_noc_OrbitalATKMember_E57E498DB50E440F83AAD2E95C9B7BBC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateAxis" xlink:label="loc_us-gaap_VariableRateAxis_D53CCF4745B674E82F20D2E95C9B59E6" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:to="loc_us-gaap_VariableRateAxis_D53CCF4745B674E82F20D2E95C9B59E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_D6078CC3F1710CB7D29BD2E95C9B98E6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_D53CCF4745B674E82F20D2E95C9B59E6" xlink:to="loc_us-gaap_VariableRateDomain_D6078CC3F1710CB7D29BD2E95C9B98E6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_VariableRateDomain" xlink:label="loc_us-gaap_VariableRateDomain_D6078CC3F1710CB7D29BD2E95C9B98E6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_D53CCF4745B674E82F20D2E95C9B59E6" xlink:to="loc_us-gaap_VariableRateDomain_D6078CC3F1710CB7D29BD2E95C9B98E6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LondonInterbankOfferedRateLIBORMember" xlink:label="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_B78147FEC3AFB79F5AAED2E95C9B7E56" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_D6078CC3F1710CB7D29BD2E95C9B98E6" xlink:to="loc_us-gaap_LondonInterbankOfferedRateLIBORMember_B78147FEC3AFB79F5AAED2E95C9B7E56" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityAxis" xlink:label="loc_us-gaap_CreditFacilityAxis_B9928FE33E813715EAFFD2E95C9C6318" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:to="loc_us-gaap_CreditFacilityAxis_B9928FE33E813715EAFFD2E95C9C6318" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_4CC0091CADCDE350C5E2D2E95C9C5C9B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_B9928FE33E813715EAFFD2E95C9C6318" xlink:to="loc_us-gaap_CreditFacilityDomain_4CC0091CADCDE350C5E2D2E95C9C5C9B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CreditFacilityDomain" xlink:label="loc_us-gaap_CreditFacilityDomain_4CC0091CADCDE350C5E2D2E95C9C5C9B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_B9928FE33E813715EAFFD2E95C9C6318" xlink:to="loc_us-gaap_CreditFacilityDomain_4CC0091CADCDE350C5E2D2E95C9C5C9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_AF904563634F8B11D073D2E95C9CCC57" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_2F675CCD0A6E056EA57BD2E95C9968D6" xlink:to="loc_us-gaap_DebtInstrumentAxis_AF904563634F8B11D073D2E95C9CCC57" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4C315880F3A7DEB8AB85D2E95C9C2477_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_AF904563634F8B11D073D2E95C9CCC57" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4C315880F3A7DEB8AB85D2E95C9C2477_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_4C315880F3A7DEB8AB85D2E95C9C2477" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_AF904563634F8B11D073D2E95C9CCC57" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_4C315880F3A7DEB8AB85D2E95C9C2477" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_TwoYearTermMemberDomain" xlink:label="loc_noc_TwoYearTermMemberDomain_C5C135A37D46CFD829F4D2E95C9C77E0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4C315880F3A7DEB8AB85D2E95C9C2477" xlink:to="loc_noc_TwoYearTermMemberDomain_C5C135A37D46CFD829F4D2E95C9C77E0" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_FiveYearTermMemberDomain" xlink:label="loc_noc_FiveYearTermMemberDomain_79D4A254D0FC16447C67D2E95C9DFCC9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_4C315880F3A7DEB8AB85D2E95C9C2477" xlink:to="loc_noc_FiveYearTermMemberDomain_79D4A254D0FC16447C67D2E95C9DFCC9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_CCFA2479997A37FF1F9FD2E95C9D7D6D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_CCFA2479997A37FF1F9FD2E95C9D7D6D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentCovenantCompliance" xlink:label="loc_us-gaap_DebtInstrumentCovenantCompliance_E01141373F8E7F96400AD2E95C9D9D9D" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_DebtInstrumentCovenantCompliance_E01141373F8E7F96400AD2E95C9D9D9D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommercialPaper" xlink:label="loc_us-gaap_CommercialPaper_BDE11FD2F4FCCEBDBBE2D2E95C9E8FC1" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_CommercialPaper_BDE11FD2F4FCCEBDBBE2D2E95C9E8FC1" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_CommercialPaperMaximumBorrowingCapacity" xlink:label="loc_noc_CommercialPaperMaximumBorrowingCapacity_7316EFCA61E4FBCE9875D2E95C9E9503" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_noc_CommercialPaperMaximumBorrowingCapacity_7316EFCA61E4FBCE9875D2E95C9E9503" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShortTermDebtWeightedAverageInterestRate" xlink:label="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_389997FEE5F21E3C15DCD2E95C9E14B8" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_ShortTermDebtWeightedAverageInterestRate_389997FEE5F21E3C15DCD2E95C9E14B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentTerm" xlink:label="loc_us-gaap_DebtInstrumentTerm_B27D70C2D5B49444FCB6D2E95C9E3641" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_DebtInstrumentTerm_B27D70C2D5B49444FCB6D2E95C9E3641" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaap_LineOfCredit_B4ABA710189F5D7E4A1CD2E95C9EF6E8" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_LineOfCredit_B4ABA710189F5D7E4A1CD2E95C9EF6E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" xlink:label="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_A5498DD4FEB90C0A3815D2E95C9EC393" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_E804ACD76D2DEAD020B0D2E95C9DF321" xlink:to="loc_us-gaap_LineOfCreditFacilityInterestRateDuringPeriod_A5498DD4FEB90C0A3815D2E95C9EC393" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CommitmentsAndContingenciesUnauditedTables" xlink:type="extended">
    <link:loc xlink:href="noc-20190630.xsd#noc_EnvironmentalRemediationRangeofFutureCostsLineItems" xlink:label="loc_noc_EnvironmentalRemediationRangeofFutureCostsLineItems_754C7941011DAE9A1852D2E95CA7182F" xlink:type="locator" />
    <link:loc xlink:href="noc-20190630.xsd#noc_EnvironmentalRemediationRangeofFutureCostsTable" xlink:label="loc_noc_EnvironmentalRemediationRangeofFutureCostsTable_7277998227C4D1E16C93D2E95CA67FE4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_noc_EnvironmentalRemediationRangeofFutureCostsLineItems_754C7941011DAE9A1852D2E95CA7182F" xlink:to="loc_noc_EnvironmentalRemediationRangeofFutureCostsTable_7277998227C4D1E16C93D2E95CA67FE4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_6DBDEC8062B57F0BB8EED2E95CA68D3D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_noc_EnvironmentalRemediationRangeofFutureCostsTable_7277998227C4D1E16C93D2E95CA67FE4" xlink:to="loc_srt_RangeAxis_6DBDEC8062B57F0BB8EED2E95CA68D3D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_350F266F201226000F75D2E95CA764CF_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_6DBDEC8062B57F0BB8EED2E95CA68D3D" xlink:to="loc_srt_RangeMember_350F266F201226000F75D2E95CA764CF_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_350F266F201226000F75D2E95CA764CF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_6DBDEC8062B57F0BB8EED2E95CA68D3D" xlink:to="loc_srt_RangeMember_350F266F201226000F75D2E95CA764CF" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_EnvironmentalRemediationTableTextBlock" xlink:label="loc_noc_EnvironmentalRemediationTableTextBlock_6894CE9EC54C48C82D8FD2E95CA7BA53" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_noc_EnvironmentalRemediationRangeofFutureCostsLineItems_754C7941011DAE9A1852D2E95CA7182F" xlink:to="loc_noc_EnvironmentalRemediationTableTextBlock_6894CE9EC54C48C82D8FD2E95CA7BA53" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_5AEB51BCAF006613822E1B0D14735AB5" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_624D37AD3F19C406F45A1B0D1473D4DF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_5AEB51BCAF006613822E1B0D14735AB5" xlink:to="loc_us-gaap_StatementTable_624D37AD3F19C406F45A1B0D1473D4DF" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RestatementAxis" xlink:label="loc_srt_RestatementAxis_438E1596D2A5CC850DE51B0D1473CBAA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_624D37AD3F19C406F45A1B0D1473D4DF" xlink:to="loc_srt_RestatementAxis_438E1596D2A5CC850DE51B0D1473CBAA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_4AF77ABFE7E995920D1F1B0D1473D3DC_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RestatementAxis_438E1596D2A5CC850DE51B0D1473CBAA" xlink:to="loc_srt_RestatementDomain_4AF77ABFE7E995920D1F1B0D1473D3DC_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RestatementDomain" xlink:label="loc_srt_RestatementDomain_4AF77ABFE7E995920D1F1B0D1473D3DC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RestatementAxis_438E1596D2A5CC850DE51B0D1473CBAA" xlink:to="loc_srt_RestatementDomain_4AF77ABFE7E995920D1F1B0D1473D3DC" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfChangesInShareholdersEquityUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_5352DC5FB76EE2C255F3D2E95E34272C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_B9E6BE93095CFAFDECE3D2E95E2DD987" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_5352DC5FB76EE2C255F3D2E95E34272C" xlink:to="loc_us-gaap_StatementTable_B9E6BE93095CFAFDECE3D2E95E2DD987" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_69E46B96BA33E7D925E0D2E95E2E51C5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_B9E6BE93095CFAFDECE3D2E95E2DD987" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_69E46B96BA33E7D925E0D2E95E2E51C5" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_69E46B96BA33E7D925E0D2E95E2E51C5" xlink:to="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_69E46B96BA33E7D925E0D2E95E2E51C5" xlink:to="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaap_CommonStockMember_24D7F923BDD5C4653E86D2E95E33ED77" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548" xlink:to="loc_us-gaap_CommonStockMember_24D7F923BDD5C4653E86D2E95E33ED77" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_24AEB139173E45DD9303D2E95E34AF9B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_24AEB139173E45DD9303D2E95E34AF9B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaap_RetainedEarningsMember_5F2D60181F75830785DFD2E95E34122F" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548" xlink:to="loc_us-gaap_RetainedEarningsMember_5F2D60181F75830785DFD2E95E34122F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F38D20F10DA7A599A36FD2E95E342564" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_CD13D042C0546125577BD2E95E2EC548" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_F38D20F10DA7A599A36FD2E95E342564" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_5352DC5FB76EE2C255F3D2E95E34272C" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockholdersEquity" xlink:label="loc_us-gaap_StockholdersEquity_6324E6C827E219D46A5FD2E95E35B38D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_us-gaap_StockholdersEquity_6324E6C827E219D46A5FD2E95E35B38D" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ImpactfromadoptionofASU201802andASU201601" xlink:label="loc_noc_ImpactfromadoptionofASU201802andASU201601_4450005CD71DAC11FC76D2E95E3594A1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_noc_ImpactfromadoptionofASU201802andASU201601_4450005CD71DAC11FC76D2E95E3594A1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_A1E2E888F50EE6CC27D6D2E95E36FD33" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_A1E2E888F50EE6CC27D6D2E95E36FD33" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaap_NetIncomeLoss_268DAF3AA131FBEC2E7CD2E95E3629C2" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_us-gaap_NetIncomeLoss_268DAF3AA131FBEC2E7CD2E95E3629C2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DividendsCommonStock" xlink:label="loc_us-gaap_DividendsCommonStock_67314BF90E60A9DD7F2CD2E95E364D29" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_us-gaap_DividendsCommonStock_67314BF90E60A9DD7F2CD2E95E364D29" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_72A276F446B6867D6FC8D2E95E3673E8" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_72A276F446B6867D6FC8D2E95E3673E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_B1EB9235121F239A3D31D2E95E366438" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_B1EB9235121F239A3D31D2E95E366438" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CommonStockDividendsPerShareDeclared" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_5A3AAAE5EA30F381709BD2E95E37AB65" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_741669AAB143D48D1684D2E95E356398" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_5A3AAAE5EA30F381709BD2E95E37AB65" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfEarningsAndComprehensiveIncomeUnaudited" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaap_StatementLineItems_5741A7C7F125717B66B2017A134365D9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaap_StatementTable_0780A9A63FC36C54C29E017A134132D2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_5741A7C7F125717B66B2017A134365D9" xlink:to="loc_us-gaap_StatementTable_0780A9A63FC36C54C29E017A134132D2" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srt_ProductOrServiceAxis_29C3FAF077E1EF63B106017A134247C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_0780A9A63FC36C54C29E017A134132D2" xlink:to="loc_srt_ProductOrServiceAxis_29C3FAF077E1EF63B106017A134247C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_F374EE6D072EB52C5479017A13428C58_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_29C3FAF077E1EF63B106017A134247C3" xlink:to="loc_srt_ProductsAndServicesDomain_F374EE6D072EB52C5479017A13428C58_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srt_ProductsAndServicesDomain_F374EE6D072EB52C5479017A13428C58" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_29C3FAF077E1EF63B106017A134247C3" xlink:to="loc_srt_ProductsAndServicesDomain_F374EE6D072EB52C5479017A13428C58" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ProductMember" xlink:label="loc_us-gaap_ProductMember_EA8D3F6E75D5EF4F21F7017A1342C086" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_F374EE6D072EB52C5479017A13428C58" xlink:to="loc_us-gaap_ProductMember_EA8D3F6E75D5EF4F21F7017A1342C086" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ServiceMember" xlink:label="loc_us-gaap_ServiceMember_38788A502CBCF396D3F9017A1343C76E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_F374EE6D072EB52C5479017A13428C58" xlink:to="loc_us-gaap_ServiceMember_38788A502CBCF396D3F9017A1343C76E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_374BD5C7B99FE981453C017A134339E1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_5741A7C7F125717B66B2017A134365D9" xlink:to="loc_us-gaap_Revenues_374BD5C7B99FE981453C017A134339E1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CostOfGoodsAndServicesSold" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_04F43134F95E29470699017A134489F6" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_5741A7C7F125717B66B2017A134365D9" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_04F43134F95E29470699017A134489F6" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfFinancialPositionUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/CondensedConsolidatedStatementsOfFinancialPositionUnauditedParentheticals" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/DocumentAndEntityInformationDocument" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityClassOfTreasuryStockLineItems" xlink:label="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfTreasuryStockTable" xlink:label="loc_us-gaap_ClassOfTreasuryStockTable_C1DF2754C22E7942BDB705942A393675" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:to="loc_us-gaap_ClassOfTreasuryStockTable_C1DF2754C22E7942BDB705942A393675" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_7F44EC693D510FC1AE7C05942A3977A7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_C1DF2754C22E7942BDB705942A393675" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_7F44EC693D510FC1AE7C05942A3977A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_6D0E38D836D182D9CCC105942A395956_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_7F44EC693D510FC1AE7C05942A3977A7" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_6D0E38D836D182D9CCC105942A395956_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_6D0E38D836D182D9CCC105942A395956" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_7F44EC693D510FC1AE7C05942A3977A7" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_6D0E38D836D182D9CCC105942A395956" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_September2015ShareRepurchaseOriginalAuthorizationMember" xlink:label="loc_noc_September2015ShareRepurchaseOriginalAuthorizationMember_1CD0714918D0C37AC4FF05942A39E133" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_6D0E38D836D182D9CCC105942A395956" xlink:to="loc_noc_September2015ShareRepurchaseOriginalAuthorizationMember_1CD0714918D0C37AC4FF05942A39E133" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_December2018ShareRepurchaseOriginalAuthorizationMember" xlink:label="loc_noc_December2018ShareRepurchaseOriginalAuthorizationMember_AD6739656218FD0249FF05942A39E0B3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_6D0E38D836D182D9CCC105942A395956" xlink:to="loc_noc_December2018ShareRepurchaseOriginalAuthorizationMember_AD6739656218FD0249FF05942A39E0B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_A884949AEB2AD108583A05942A4958BA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_A884949AEB2AD108583A05942A4958BA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchaseProgramAuthorizedAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_FEE30E20372970F73B8D05942A493BE7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:to="loc_us-gaap_StockRepurchaseProgramAuthorizedAmount1_FEE30E20372970F73B8D05942A493BE7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockSharesRetired" xlink:label="loc_us-gaap_TreasuryStockSharesRetired_92A7BA708CCE9C10EE6305942A492B90" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:to="loc_us-gaap_TreasuryStockSharesRetired_92A7BA708CCE9C10EE6305942A492B90" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockAcquiredAverageCostPerShare" xlink:label="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_34DB28409B329205F47605942A49D736" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:to="loc_us-gaap_TreasuryStockAcquiredAverageCostPerShare_34DB28409B329205F47605942A49D736" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_33F45B742B35F9FECBE905942A499CF1" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_33F45B742B35F9FECBE905942A499CF1" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ShareRepurchasesTableAbstract" xlink:label="loc_noc_ShareRepurchasesTableAbstract_F8AA9B0664D22981E71905942A499259" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_EA3672088D70CDA0A1F205942A398D1E" xlink:to="loc_noc_ShareRepurchasesTableAbstract_F8AA9B0664D22981E71905942A499259" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TreasuryStockValueAcquiredParValueMethod" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredParValueMethod_E84934FCB85BD6CA18FB05942A49FF28" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_noc_ShareRepurchasesTableAbstract_F8AA9B0664D22981E71905942A499259" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredParValueMethod_E84934FCB85BD6CA18FB05942A49FF28" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_1DEADD7FA1D6830EBF1C05942A49F095" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_noc_ShareRepurchasesTableAbstract_F8AA9B0664D22981E71905942A499259" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_1DEADD7FA1D6830EBF1C05942A49F095" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedDetails2" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EquityClassOfTreasuryStockLineItems" xlink:label="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ClassOfTreasuryStockTable" xlink:label="loc_us-gaap_ClassOfTreasuryStockTable_28ADED18E9B8872E44FF05942A3953EA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:to="loc_us-gaap_ClassOfTreasuryStockTable_28ADED18E9B8872E44FF05942A3953EA" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramAxis" xlink:label="loc_us-gaap_ShareRepurchaseProgramAxis_490691DBBB9BB9328C7B05942A39FBF4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ClassOfTreasuryStockTable_28ADED18E9B8872E44FF05942A3953EA" xlink:to="loc_us-gaap_ShareRepurchaseProgramAxis_490691DBBB9BB9328C7B05942A39FBF4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_E59EA841F26241298B5A05942A39964B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_490691DBBB9BB9328C7B05942A39FBF4" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_E59EA841F26241298B5A05942A39964B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareRepurchaseProgramDomain" xlink:label="loc_us-gaap_ShareRepurchaseProgramDomain_E59EA841F26241298B5A05942A39964B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareRepurchaseProgramAxis_490691DBBB9BB9328C7B05942A39FBF4" xlink:to="loc_us-gaap_ShareRepurchaseProgramDomain_E59EA841F26241298B5A05942A39964B" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_September2015ShareRepurchaseOriginalAuthorizationMember" xlink:label="loc_noc_September2015ShareRepurchaseOriginalAuthorizationMember_7AB2634CEF45F679AFAC05942A393367" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareRepurchaseProgramDomain_E59EA841F26241298B5A05942A39964B" xlink:to="loc_noc_September2015ShareRepurchaseOriginalAuthorizationMember_7AB2634CEF45F679AFAC05942A393367" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AcceleratedShareRepurchase" xlink:label="loc_noc_AcceleratedShareRepurchase_DA2AF3F79F672653967605942A394625" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:to="loc_noc_AcceleratedShareRepurchase_DA2AF3F79F672653967605942A394625" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AcceleratedShareRepurchasesPayment" xlink:label="loc_noc_AcceleratedShareRepurchasesPayment_D3A0204D92C8819CB8C105942A398D9E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:to="loc_noc_AcceleratedShareRepurchasesPayment_D3A0204D92C8819CB8C105942A398D9E" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_Acceleratedsharerepurchaseinitialreceiptshares" xlink:label="loc_noc_Acceleratedsharerepurchaseinitialreceiptshares_27895E789A57F039CCD205942A394146" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:to="loc_noc_Acceleratedsharerepurchaseinitialreceiptshares_27895E789A57F039CCD205942A394146" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AcceleratedShareRepurchaseInitialReceiptMonetary" xlink:label="loc_noc_AcceleratedShareRepurchaseInitialReceiptMonetary_F4E306FCE66B7DACF5CB05942A39D64D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:to="loc_noc_AcceleratedShareRepurchaseInitialReceiptMonetary_F4E306FCE66B7DACF5CB05942A39D64D" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AcceleratedShareRepurchaseFinalReceiptShares" xlink:label="loc_noc_AcceleratedShareRepurchaseFinalReceiptShares_771EAC5461A9121A5D9C05942A39E975" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:to="loc_noc_AcceleratedShareRepurchaseFinalReceiptShares_771EAC5461A9121A5D9C05942A39E975" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AcceleratedShareRepurchasesFinalPricePaidPerShare" xlink:label="loc_us-gaap_AcceleratedShareRepurchasesFinalPricePaidPerShare_CE9BBF9D8EABBB45953005942A39BC6A" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityClassOfTreasuryStockLineItems_3BF9909DE68E00EA821E05942A399D61" xlink:to="loc_us-gaap_AcceleratedShareRepurchasesFinalPricePaidPerShare_CE9BBF9D8EABBB45953005942A39BC6A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/EarningsPerShareShareRepurchasesAndDividendsOnCommonStockUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_FE9678029C5B4D247F48D2E95CD76836" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_D98C9B1281EB105C1350D2E95CD40E43" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_FE9678029C5B4D247F48D2E95CD76836" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_D98C9B1281EB105C1350D2E95CD40E43" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByMeasurementFrequencyAxis" xlink:label="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1060199B0A379A425E26D2E95CD53491" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_D98C9B1281EB105C1350D2E95CD40E43" xlink:to="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1060199B0A379A425E26D2E95CD53491" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_FD5B8CD001C08B1D0C6AD2E95CD57190_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1060199B0A379A425E26D2E95CD53491" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_FD5B8CD001C08B1D0C6AD2E95CD57190_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementFrequencyDomain" xlink:label="loc_us-gaap_FairValueMeasurementFrequencyDomain_FD5B8CD001C08B1D0C6AD2E95CD57190" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementFrequencyAxis_1060199B0A379A425E26D2E95CD53491" xlink:to="loc_us-gaap_FairValueMeasurementFrequencyDomain_FD5B8CD001C08B1D0C6AD2E95CD57190" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsRecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsRecurringMember_8B1239B932966E55D217D2E95CD50AAE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_FD5B8CD001C08B1D0C6AD2E95CD57190" xlink:to="loc_us-gaap_FairValueMeasurementsRecurringMember_8B1239B932966E55D217D2E95CD50AAE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsNonrecurringMember" xlink:label="loc_us-gaap_FairValueMeasurementsNonrecurringMember_8C1011323ADB8169172CD2E95CD6E8C3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementFrequencyDomain_FD5B8CD001C08B1D0C6AD2E95CD57190" xlink:to="loc_us-gaap_FairValueMeasurementsNonrecurringMember_8C1011323ADB8169172CD2E95CD6E8C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_EB5083F22E29A94D1A61D2E95CD6A9D9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_D98C9B1281EB105C1350D2E95CD40E43" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_EB5083F22E29A94D1A61D2E95CD6A9D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_DC74088DA39CC488CD80D2E95CD6DFC0_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_EB5083F22E29A94D1A61D2E95CD6A9D9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_DC74088DA39CC488CD80D2E95CD6DFC0_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_DC74088DA39CC488CD80D2E95CD6DFC0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_EB5083F22E29A94D1A61D2E95CD6A9D9" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_DC74088DA39CC488CD80D2E95CD6DFC0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_3E5A8DD239569B4CE0FDD2E95CD60DCE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_DC74088DA39CC488CD80D2E95CD6DFC0" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_3E5A8DD239569B4CE0FDD2E95CD60DCE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_77422CB5EF6E387307CFD2E95CD74406" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_DC74088DA39CC488CD80D2E95CD6DFC0" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_77422CB5EF6E387307CFD2E95CD74406" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MarketableSecurities" xlink:label="loc_us-gaap_MarketableSecurities_87EDE649554D8A64D258D2E95CD74E20" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_FE9678029C5B4D247F48D2E95CD76836" xlink:to="loc_us-gaap_MarketableSecurities_87EDE649554D8A64D258D2E95CD74E20" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet" xlink:label="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_766F4D0EA794EDD9C82BD2E95CD7A965" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_FE9678029C5B4D247F48D2E95CD76836" xlink:to="loc_us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet_766F4D0EA794EDD9C82BD2E95CD7A965" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedDetails2" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_73BA3C979CEC4A05A462D2E95CCEEF49" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FairValueByBalanceSheetGroupingTable" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_B0CC6E966B003AD78C7CD2E95CCC04CD" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_73BA3C979CEC4A05A462D2E95CCEEF49" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_B0CC6E966B003AD78C7CD2E95CCC04CD" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentRiskAxis" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_2340AC82C57E68BA553DD2E95CCCACD4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_B0CC6E966B003AD78C7CD2E95CCC04CD" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_2340AC82C57E68BA553DD2E95CCCACD4" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2340AC82C57E68BA553DD2E95CCCACD4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeContractTypeDomain" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_2340AC82C57E68BA553DD2E95CCCACD4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_CopperMember" xlink:label="loc_noc_CopperMember_FFB358D0872E7F7CDD5AD2E95CCDD7A4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C" xlink:to="loc_noc_CopperMember_FFB358D0872E7F7CDD5AD2E95CCDD7A4" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ZincMemberDomain" xlink:label="loc_noc_ZincMemberDomain_5CAD6371B9B83A10C6E9D2E95CCDD425" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C" xlink:to="loc_noc_ZincMemberDomain_5CAD6371B9B83A10C6E9D2E95CCDD425" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ForeignExchangeForwardMember" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_06C66F5EA1D355FEEA22D2E95CCD3DAB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_06C66F5EA1D355FEEA22D2E95CCD3DAB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_816CD23D4B2F0BC8AC75D2E95CCDE2AF" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_6240FD68ED2D5D5EEE39D2E95CCCA12C" xlink:to="loc_us-gaap_CashFlowHedgingMember_816CD23D4B2F0BC8AC75D2E95CCDE2AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04CE0DD5781A9CD0CD14D2E95CCEC464" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_B0CC6E966B003AD78C7CD2E95CCC04CD" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04CE0DD5781A9CD0CD14D2E95CCEC464" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_C40E5BB07740AF072934D2E95CCEE888_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04CE0DD5781A9CD0CD14D2E95CCEC464" xlink:to="loc_us-gaap_HedgingRelationshipDomain_C40E5BB07740AF072934D2E95CCEE888_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_HedgingRelationshipDomain" xlink:label="loc_us-gaap_HedgingRelationshipDomain_C40E5BB07740AF072934D2E95CCEE888" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_04CE0DD5781A9CD0CD14D2E95CCEC464" xlink:to="loc_us-gaap_HedgingRelationshipDomain_C40E5BB07740AF072934D2E95CCEE888" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CashFlowHedgingMember" xlink:label="loc_us-gaap_CashFlowHedgingMember_7C3FDAE9DBBB43DD3B2CD2E95CCECEDF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_C40E5BB07740AF072934D2E95CCEE888" xlink:to="loc_us-gaap_CashFlowHedgingMember_7C3FDAE9DBBB43DD3B2CD2E95CCECEDF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeNonmonetaryNotionalAmountMass" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_4568DEF81088A3953F20D2E95CCEC10A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_73BA3C979CEC4A05A462D2E95CCEEF49" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmountMass_4568DEF81088A3953F20D2E95CCEC10A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract" xlink:label="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract_2C2C7B5901B325FA34FDD2E95CCFF37C" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_73BA3C979CEC4A05A462D2E95CCEEF49" xlink:to="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract_2C2C7B5901B325FA34FDD2E95CCFF37C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.sec.gov/invest/2013/invest-2013-01-31.xsd#invest_DerivativeNotionalAmount" xlink:label="loc_invest_DerivativeNotionalAmount_73E03D7D996C1511FC19D2E95CCFE46A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeInstrumentsAndHedgingActivitiesDisclosureAbstract_2C2C7B5901B325FA34FDD2E95CCFF37C" xlink:to="loc_invest_DerivativeNotionalAmount_73E03D7D996C1511FC19D2E95CCFE46A" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedFairValueOfFinancialInstrumentsUnauditedDetails3" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionLineItems" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_E25105ABA3B21CC8357DD2E95CC64A38" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_DF0587F4DF7A6466E987D2E95CC4777D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E25105ABA3B21CC8357DD2E95CC64A38" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_DF0587F4DF7A6466E987D2E95CC4777D" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentAxis" xlink:label="loc_us-gaap_DebtInstrumentAxis_CC98FBED4794C1A4F67BD2E95CC4098D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_DF0587F4DF7A6466E987D2E95CC4777D" xlink:to="loc_us-gaap_DebtInstrumentAxis_CC98FBED4794C1A4F67BD2E95CC4098D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_46C057092506D504761ED2E95CC50EBA_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_CC98FBED4794C1A4F67BD2E95CC4098D" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_46C057092506D504761ED2E95CC50EBA_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtInstrumentNameDomain" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_46C057092506D504761ED2E95CC50EBA" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_CC98FBED4794C1A4F67BD2E95CC4098D" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_46C057092506D504761ED2E95CC50EBA" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_BADBD8EDA1F1A1264568D2E95CC5B8B8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_DF0587F4DF7A6466E987D2E95CC4777D" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_BADBD8EDA1F1A1264568D2E95CC5B8B8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8A5F693E57284E50B682D2E95CC55BDE_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_BADBD8EDA1F1A1264568D2E95CC5B8B8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8A5F693E57284E50B682D2E95CC55BDE_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8A5F693E57284E50B682D2E95CC55BDE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_BADBD8EDA1F1A1264568D2E95CC5B8B8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8A5F693E57284E50B682D2E95CC55BDE" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_OrbitalATKMember" xlink:label="loc_noc_OrbitalATKMember_47E7F97F8A37A4D5F919D2E95CC6F3ED" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_8A5F693E57284E50B682D2E95CC55BDE" xlink:to="loc_noc_OrbitalATKMember_47E7F97F8A37A4D5F919D2E95CC6F3ED" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeAxis" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_D80DF641684C161C3187D2E95CC6D801" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_DF0587F4DF7A6466E987D2E95CC4777D" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_D80DF641684C161C3187D2E95CC6D801" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_07E973C9F6F47307ADF6D2E95CC6FA8E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_D80DF641684C161C3187D2E95CC6D801" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_07E973C9F6F47307ADF6D2E95CC6FA8E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongtermDebtTypeDomain" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_07E973C9F6F47307ADF6D2E95CC6FA8E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_D80DF641684C161C3187D2E95CC6D801" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_07E973C9F6F47307ADF6D2E95CC6FA8E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LongTermDebtFairValue" xlink:label="loc_us-gaap_LongTermDebtFairValue_DC6902B38CFF3CE6A00ED2E95CC7CB37" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E25105ABA3B21CC8357DD2E95CC64A38" xlink:to="loc_us-gaap_LongTermDebtFairValue_DC6902B38CFF3CE6A00ED2E95CC7CB37" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DebtAndCapitalLeaseObligations" xlink:label="loc_us-gaap_DebtAndCapitalLeaseObligations_4C1B6FA96964C2ACBB70D2E95CC70A06" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E25105ABA3B21CC8357DD2E95CC64A38" xlink:to="loc_us-gaap_DebtAndCapitalLeaseObligations_4C1B6FA96964C2ACBB70D2E95CC70A06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_502E83CA2C0D44D1124AD2E95CC7A362" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_E25105ABA3B21CC8357DD2E95CC64A38" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_502E83CA2C0D44D1124AD2E95CC7A362" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/FairValueOfFinancialInstrumentsUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/IncomeTaxesUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/IncomeTaxesUnauditedDetails1" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/IncomeTaxesUnauditedDetails2" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/IncomeTaxesUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/InvestigationsClaimsAndLitigationUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/InvestigationsClaimsAndLitigationUnauditedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_266924AFBF2E6B42488CD2E95CB111C3" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:to="loc_srt_RangeAxis_266924AFBF2E6B42488CD2E95CB111C3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_CF3DE2102063801CE6FAD2E95CB2D74F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_266924AFBF2E6B42488CD2E95CB111C3" xlink:to="loc_srt_RangeMember_CF3DE2102063801CE6FAD2E95CB2D74F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_CF3DE2102063801CE6FAD2E95CB2D74F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_266924AFBF2E6B42488CD2E95CB111C3" xlink:to="loc_srt_RangeMember_CF3DE2102063801CE6FAD2E95CB2D74F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_AB3977C1469DEAC4B5E4D2E95CB2D21A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_CF3DE2102063801CE6FAD2E95CB2D74F" xlink:to="loc_srt_MaximumMember_AB3977C1469DEAC4B5E4D2E95CB2D21A" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ClaimAmountAxis" xlink:label="loc_noc_ClaimAmountAxis_5E6437120455598B6B1AD2E95CB30656" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:to="loc_noc_ClaimAmountAxis_5E6437120455598B6B1AD2E95CB30656" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ClaimAmountDomain" xlink:label="loc_noc_ClaimAmountDomain_B2DFB8CE3F58CFC1B994D2E95CB330B1_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_noc_ClaimAmountAxis_5E6437120455598B6B1AD2E95CB30656" xlink:to="loc_noc_ClaimAmountDomain_B2DFB8CE3F58CFC1B994D2E95CB330B1_default" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ClaimAmountDomain" xlink:label="loc_noc_ClaimAmountDomain_B2DFB8CE3F58CFC1B994D2E95CB330B1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_noc_ClaimAmountAxis_5E6437120455598B6B1AD2E95CB30656" xlink:to="loc_noc_ClaimAmountDomain_B2DFB8CE3F58CFC1B994D2E95CB330B1" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_InitialClaimMember" xlink:label="loc_noc_InitialClaimMember_1AFF3E57113FD2569968D2E95CB3832E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_noc_ClaimAmountDomain_B2DFB8CE3F58CFC1B994D2E95CB330B1" xlink:to="loc_noc_InitialClaimMember_1AFF3E57113FD2569968D2E95CB3832E" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_IncrementalclaimMember" xlink:label="loc_noc_IncrementalclaimMember_4A7A85BF81F2F4B8A3E9D2E95CB3E623" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_noc_ClaimAmountDomain_B2DFB8CE3F58CFC1B994D2E95CB330B1" xlink:to="loc_noc_IncrementalclaimMember_4A7A85BF81F2F4B8A3E9D2E95CB3E623" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_729FEA62976F30B3549CD2E95CB34A77" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_729FEA62976F30B3549CD2E95CB34A77" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_D4535D7FB60663126806D2E95CB4AB33_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_729FEA62976F30B3549CD2E95CB34A77" xlink:to="loc_us-gaap_LossContingencyNatureDomain_D4535D7FB60663126806D2E95CB4AB33_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNatureDomain" xlink:label="loc_us-gaap_LossContingencyNatureDomain_D4535D7FB60663126806D2E95CB4AB33" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_729FEA62976F30B3549CD2E95CB34A77" xlink:to="loc_us-gaap_LossContingencyNatureDomain_D4535D7FB60663126806D2E95CB4AB33" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_UnitedStatesPostalServiceMember" xlink:label="loc_noc_UnitedStatesPostalServiceMember_1786CC37E5C800C3EADDD2E95CB4CE29" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_D4535D7FB60663126806D2E95CB4AB33" xlink:to="loc_noc_UnitedStatesPostalServiceMember_1786CC37E5C800C3EADDD2E95CB4CE29" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_SolysticMatterMember" xlink:label="loc_noc_SolysticMatterMember_2B1A225E1209D2207310D2E95CB4B434" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_D4535D7FB60663126806D2E95CB4AB33" xlink:to="loc_noc_SolysticMatterMember_2B1A225E1209D2207310D2E95CB4B434" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainContingenciesByNatureAxis" xlink:label="loc_us-gaap_GainContingenciesByNatureAxis_8CFE99161277A6BAC2F2D2E95CB54076" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:to="loc_us-gaap_GainContingenciesByNatureAxis_8CFE99161277A6BAC2F2D2E95CB54076" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainContingencyNatureDomain" xlink:label="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GainContingenciesByNatureAxis_8CFE99161277A6BAC2F2D2E95CB54076" xlink:to="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainContingencyNatureDomain" xlink:label="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GainContingenciesByNatureAxis_8CFE99161277A6BAC2F2D2E95CB54076" xlink:to="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_UnpaidPortionsOfContractPriceAndDirectCostsIncurredMember" xlink:label="loc_noc_UnpaidPortionsOfContractPriceAndDirectCostsIncurredMember_726C5B5C3C222377F277D2E95CB54CA7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2" xlink:to="loc_noc_UnpaidPortionsOfContractPriceAndDirectCostsIncurredMember_726C5B5C3C222377F277D2E95CB54CA7" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_SolysticMatterMember" xlink:label="loc_noc_SolysticMatterMember_9846E244DDD25E7EBE1DD2E95CB5382F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2" xlink:to="loc_noc_SolysticMatterMember_9846E244DDD25E7EBE1DD2E95CB5382F" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_UnitedStatesPostalServiceMember" xlink:label="loc_noc_UnitedStatesPostalServiceMember_EB2E2F69A6D9B753FF0FD2E95CB6E334" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2" xlink:to="loc_noc_UnitedStatesPostalServiceMember_EB2E2F69A6D9B753FF0FD2E95CB6E334" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ActsAndOmissionsWithAdverseAffectsOnPerformanceAndObligationsMember" xlink:label="loc_noc_ActsAndOmissionsWithAdverseAffectsOnPerformanceAndObligationsMember_86CFE0EC9B980FDB598FD2E95CB6F406" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainContingencyNatureDomain_6FDA2B59C72DDA7097E6D2E95CB510B2" xlink:to="loc_noc_ActsAndOmissionsWithAdverseAffectsOnPerformanceAndObligationsMember_86CFE0EC9B980FDB598FD2E95CB6F406" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseAxis" xlink:label="loc_srt_LitigationCaseAxis_BC4455C2A87EB00A8CA6D2E95CB6E776" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:to="loc_srt_LitigationCaseAxis_BC4455C2A87EB00A8CA6D2E95CB6E776" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_BC4455C2A87EB00A8CA6D2E95CB6E776" xlink:to="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_BC4455C2A87EB00A8CA6D2E95CB6E776" xlink:to="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_USGovernmentMember" xlink:label="loc_noc_USGovernmentMember_32D73D802A931DBB8B0FD2E95CB694CC" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837" xlink:to="loc_noc_USGovernmentMember_32D73D802A931DBB8B0FD2E95CB694CC" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_UnitedStatesPostalServiceMember" xlink:label="loc_noc_UnitedStatesPostalServiceMember_2D6F42A57C6CB711E0DDD2E95CB7F01F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837" xlink:to="loc_noc_UnitedStatesPostalServiceMember_2D6F42A57C6CB711E0DDD2E95CB7F01F" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_FalseClaimsActMember" xlink:label="loc_noc_FalseClaimsActMember_C3F24BE8FF4C00FE947AD2E95CB75FC8" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837" xlink:to="loc_noc_FalseClaimsActMember_C3F24BE8FF4C00FE947AD2E95CB75FC8" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_SolysticMatterMember" xlink:label="loc_noc_SolysticMatterMember_37DE6547121EA3304199D2E95CB75652" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837" xlink:to="loc_noc_SolysticMatterMember_37DE6547121EA3304199D2E95CB75652" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_OrbitalATKMember" xlink:label="loc_noc_OrbitalATKMember_D7E443FCFA6272781114D2E95CB70D02" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_B6D7E4AFACE4DB2E1E41D2E95CB65837" xlink:to="loc_noc_OrbitalATKMember_D7E443FCFA6272781114D2E95CB70D02" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LitigationStatusAxis" xlink:label="loc_us-gaap_LitigationStatusAxis_91D7D1BE9CDDA628FF2DD2E95CB77B71" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_A1F8456FFF78CF423FCED2E95CB14677" xlink:to="loc_us-gaap_LitigationStatusAxis_91D7D1BE9CDDA628FF2DD2E95CB77B71" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_EE8BE3157F0B71913B7ED2E95CB82CB6_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LitigationStatusAxis_91D7D1BE9CDDA628FF2DD2E95CB77B71" xlink:to="loc_us-gaap_LitigationStatusDomain_EE8BE3157F0B71913B7ED2E95CB82CB6_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LitigationStatusDomain" xlink:label="loc_us-gaap_LitigationStatusDomain_EE8BE3157F0B71913B7ED2E95CB82CB6" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LitigationStatusAxis_91D7D1BE9CDDA628FF2DD2E95CB77B71" xlink:to="loc_us-gaap_LitigationStatusDomain_EE8BE3157F0B71913B7ED2E95CB82CB6" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ThreatenedLitigationMember" xlink:label="loc_us-gaap_ThreatenedLitigationMember_ED4EB23790ACADAD3D59D2E95CB8B5EE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LitigationStatusDomain_EE8BE3157F0B71913B7ED2E95CB82CB6" xlink:to="loc_us-gaap_ThreatenedLitigationMember_ED4EB23790ACADAD3D59D2E95CB8B5EE" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_ContractAward" xlink:label="loc_noc_ContractAward_BB78A67411627C47734AD2E95CB913BE" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_noc_ContractAward_BB78A67411627C47734AD2E95CB913BE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_UnbilledReceivablesCurrent" xlink:label="loc_us-gaap_UnbilledReceivablesCurrent_EFCDD5ED6C2E3A537757D2E95CB9C09B" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_us-gaap_UnbilledReceivablesCurrent_EFCDD5ED6C2E3A537757D2E95CB9C09B" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_GainContingencyUnrecordedAmount" xlink:label="loc_us-gaap_GainContingencyUnrecordedAmount_CA9D4F92D4F67CC80323D2E95CB9B83C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_us-gaap_GainContingencyUnrecordedAmount_CA9D4F92D4F67CC80323D2E95CB9B83C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_4E0FFAAF4242CADF2689D2E95CB979D1" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_4E0FFAAF4242CADF2689D2E95CB979D1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyDamagesSoughtValue" xlink:label="loc_us-gaap_LossContingencyDamagesSoughtValue_99EC5DB2D8B0C9B07943D2E95CB9CD76" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_us-gaap_LossContingencyDamagesSoughtValue_99EC5DB2D8B0C9B07943D2E95CB9CD76" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_CounterclaimForDamagesSought" xlink:label="loc_noc_CounterclaimForDamagesSought_F64AA7D4AE6B46FC05D7D2E95CBA5A22" xlink:type="locator" />
    <link:definitionArc order="6" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_noc_CounterclaimForDamagesSought_F64AA7D4AE6B46FC05D7D2E95CBA5A22" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_Counterclaim" xlink:label="loc_noc_Counterclaim_DDE6D118BAEF11F1C107D2E95CBA98E0" xlink:type="locator" />
    <link:definitionArc order="7" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_noc_Counterclaim_DDE6D118BAEF11F1C107D2E95CBA98E0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyDamagesAwardedValue" xlink:label="loc_us-gaap_LossContingencyDamagesAwardedValue_B678F551AAD3778FC2A2D2E95CBAE75A" xlink:type="locator" />
    <link:definitionArc order="8" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_us-gaap_LossContingencyDamagesAwardedValue_B678F551AAD3778FC2A2D2E95CBAE75A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_LossContingencyNumberOfDefendants" xlink:label="loc_us-gaap_LossContingencyNumberOfDefendants_A56D726D4F41CC46D652D2E95CBACC93" xlink:type="locator" />
    <link:definitionArc order="9" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_1898F86C78DEB7910A62D2E95CB84FE9" xlink:to="loc_us-gaap_LossContingencyNumberOfDefendants_A56D726D4F41CC46D652D2E95CBACC93" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/LeasesUnauditedFutureMinimumLeasePaymentsUnder840Details" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/LeasesUnauditedLeaseBalanceSheetDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/LeasesUnauditedLeaseMaturitiesDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/LeasesUnauditedLeaseOtherSupplementalInformationDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/LeasesUnauditedLeasesTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/LeasesUnauditedNotes" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/LeasesUnauditedTotalLeaseCostDetails" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/RetirementBenefitsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/RetirementBenefitsUnauditedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_343AA05AAA31D962499FD2E95C80A2AB" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_3D351B3459BE90EAB415D2E95C7E28D4" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_343AA05AAA31D962499FD2E95C80A2AB" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_3D351B3459BE90EAB415D2E95C7E28D4" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanTypeAxis" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_FFE49996216798F63178D2E95C7F1F39" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_3D351B3459BE90EAB415D2E95C7E28D4" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_FFE49996216798F63178D2E95C7F1F39" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_C7DD977EF4A9B7F1C2BBD2E95C7F1101_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_FFE49996216798F63178D2E95C7F1F39" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_C7DD977EF4A9B7F1C2BBD2E95C7F1101_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RetirementPlanTypeDomain" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_C7DD977EF4A9B7F1C2BBD2E95C7F1101" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_FFE49996216798F63178D2E95C7F1F39" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_C7DD977EF4A9B7F1C2BBD2E95C7F1101" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PensionPlansDefinedBenefitMember" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_BC1D49567AD90B937EBDD2E95C7F9324" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_C7DD977EF4A9B7F1C2BBD2E95C7F1101" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_BC1D49567AD90B937EBDD2E95C7F9324" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember" xlink:label="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_E3A9FD744D9E2180BE98D2E95C80B170" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_C7DD977EF4A9B7F1C2BBD2E95C7F1101" xlink:to="loc_us-gaap_OtherPostretirementBenefitPlansDefinedBenefitMember_E3A9FD744D9E2180BE98D2E95C80B170" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_6E588D959E1F91E80E92D2E95C806E5E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_343AA05AAA31D962499FD2E95C80A2AB" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_6E588D959E1F91E80E92D2E95C806E5E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanServiceCost" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_8C96C0F9C92165B8B64BD2E95C805989" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_6E588D959E1F91E80E92D2E95C806E5E" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_8C96C0F9C92165B8B64BD2E95C805989" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanInterestCost" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_19F045F2BA92F36E7F3DD2E95C816672" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_6E588D959E1F91E80E92D2E95C806E5E" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_19F045F2BA92F36E7F3DD2E95C816672" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_281169AFBA2036C370B7D2E95C817CAD" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_6E588D959E1F91E80E92D2E95C806E5E" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_281169AFBA2036C370B7D2E95C817CAD" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_6F5E34AE9CFB24D4CD5BD2E95C81A34E" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_6E588D959E1F91E80E92D2E95C806E5E" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfPriorServiceCostCredit_6F5E34AE9CFB24D4CD5BD2E95C81A34E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_D12216CA119671B235BED2E95C810EAF" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCostAbstract_6E588D959E1F91E80E92D2E95C806E5E" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_D12216CA119671B235BED2E95C810EAF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedBenefitPlanContributionsByEmployer" xlink:label="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_BAE2A55C84530532F4C4D2E95C810916" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_343AA05AAA31D962499FD2E95C80A2AB" xlink:to="loc_us-gaap_DefinedBenefitPlanContributionsByEmployer_BAE2A55C84530532F4C4D2E95C810916" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedContributionPensionAndOtherPostretirementPlansDisclosureAbstract" xlink:label="loc_us-gaap_DefinedContributionPensionAndOtherPostretirementPlansDisclosureAbstract_6DFC56896DF8D0392EBCD2E95C815D46" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_343AA05AAA31D962499FD2E95C80A2AB" xlink:to="loc_us-gaap_DefinedContributionPensionAndOtherPostretirementPlansDisclosureAbstract_6DFC56896DF8D0392EBCD2E95C815D46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_ECF899BE01F6AE2E429FD2E95C8214FF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedContributionPensionAndOtherPostretirementPlansDisclosureAbstract_6DFC56896DF8D0392EBCD2E95C815D46" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_ECF899BE01F6AE2E429FD2E95C8214FF" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/RetirementBenefitsUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/SegmentInformationUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails1" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_3A5AC922847A487EDD9805EF287CBE37" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E6646E5B41653A14B45905EF2872DDD9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3A5AC922847A487EDD9805EF287CBE37" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E6646E5B41653A14B45905EF2872DDD9" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_33F36F903416E4FA7EBD05EF28724DD1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E6646E5B41653A14B45905EF2872DDD9" xlink:to="loc_srt_ConsolidationItemsAxis_33F36F903416E4FA7EBD05EF28724DD1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_33F36F903416E4FA7EBD05EF28724DD1" xlink:to="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_33F36F903416E4FA7EBD05EF28724DD1" xlink:to="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_7E4BFB6840510EA6CA0005EF28721430" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763" xlink:to="loc_us-gaap_OperatingSegmentsMember_7E4BFB6840510EA6CA0005EF28721430" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_76001D3B29133FAEE66305EF28720E06" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763" xlink:to="loc_us-gaap_IntersegmentEliminationMember_76001D3B29133FAEE66305EF28720E06" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_MaterialReconcilingItemsMember" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_CD9F6AC2990A3FF760ED05EF28720652" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_CD9F6AC2990A3FF760ED05EF28720652" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_CorporateNonSegmentMember" xlink:label="loc_us-gaap_CorporateNonSegmentMember_BB21B301BB8BC9DAB09A05EF28723E83" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_DE143317F5360CD886A705EF28724763" xlink:to="loc_us-gaap_CorporateNonSegmentMember_BB21B301BB8BC9DAB09A05EF28723E83" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_B09125C496542DC828D605EF287292AF" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_E6646E5B41653A14B45905EF2872DDD9" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_B09125C496542DC828D605EF287292AF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B09125C496542DC828D605EF287292AF" xlink:to="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_B09125C496542DC828D605EF287292AF" xlink:to="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AerospaceSystemsMember" xlink:label="loc_noc_AerospaceSystemsMember_076390020ABFA11D17FD05EF28728B9D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B" xlink:to="loc_noc_AerospaceSystemsMember_076390020ABFA11D17FD05EF28728B9D" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_InnovationSystemsMember" xlink:label="loc_noc_InnovationSystemsMember_7917DA86718A2DC0D57C05EF287C8FF8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B" xlink:to="loc_noc_InnovationSystemsMember_7917DA86718A2DC0D57C05EF287C8FF8" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_MissionSystemsMember" xlink:label="loc_noc_MissionSystemsMember_B8259717B8708ED97F4005EF287C7405" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B" xlink:to="loc_noc_MissionSystemsMember_B8259717B8708ED97F4005EF287C7405" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_TechnologyServicesMember" xlink:label="loc_noc_TechnologyServicesMember_D6568544EDD8B8FE981905EF287C57D9" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B" xlink:to="loc_noc_TechnologyServicesMember_D6568544EDD8B8FE981905EF287C57D9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_BE7BA315C21961F3EA2605EF287C8541" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_55012031DFB3A152465F05EF2872577B" xlink:to="loc_us-gaap_IntersegmentEliminationMember_BE7BA315C21961F3EA2605EF287C8541" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaap_NumberOfReportableSegments_30AA1C7D940B3FA92F6505EF287C02FF" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3A5AC922847A487EDD9805EF287CBE37" xlink:to="loc_us-gaap_NumberOfReportableSegments_30AA1C7D940B3FA92F6505EF287C02FF" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_7538612C1FEAA06BEDD305EF287C04B3" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3A5AC922847A487EDD9805EF287CBE37" xlink:to="loc_us-gaap_Revenues_7538612C1FEAA06BEDD305EF287C04B3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaap_OperatingIncomeLoss_C7DFB7803E396AE636E405EF287CFFC2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3A5AC922847A487EDD9805EF287CBE37" xlink:to="loc_us-gaap_OperatingIncomeLoss_C7DFB7803E396AE636E405EF287CFFC2" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_NetFASserviceCASpensionadjustment" xlink:label="loc_noc_NetFASserviceCASpensionadjustment_7D496695371788E0B2FD05EF287CA488" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_3A5AC922847A487EDD9805EF287CBE37" xlink:to="loc_noc_NetFASserviceCASpensionadjustment_7D496695371788E0B2FD05EF287CA488" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails2" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_EntityWideRevenueMajorCustomerLineItems" xlink:label="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_2CDB94F6E41F13EA7FCAD2E95C2C8DC1" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable" xlink:label="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_DFE773884F1074F834D0D2E95C263118" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_2CDB94F6E41F13EA7FCAD2E95C2C8DC1" xlink:to="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_DFE773884F1074F834D0D2E95C263118" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_BBBF890EC74B93B357DED2E95C263CE0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_DFE773884F1074F834D0D2E95C263118" xlink:to="loc_srt_ConsolidationItemsAxis_BBBF890EC74B93B357DED2E95C263CE0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_1E7E2B931F75EBEDF231D2E95C26DB11_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_BBBF890EC74B93B357DED2E95C263CE0" xlink:to="loc_srt_ConsolidationItemsDomain_1E7E2B931F75EBEDF231D2E95C26DB11_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_1E7E2B931F75EBEDF231D2E95C26DB11" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_BBBF890EC74B93B357DED2E95C263CE0" xlink:to="loc_srt_ConsolidationItemsDomain_1E7E2B931F75EBEDF231D2E95C26DB11" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_1859624CD1A8AE139C10D2E95C276A3A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_1E7E2B931F75EBEDF231D2E95C26DB11" xlink:to="loc_us-gaap_OperatingSegmentsMember_1859624CD1A8AE139C10D2E95C276A3A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MajorCustomersAxis" xlink:label="loc_srt_MajorCustomersAxis_478A045EF7305DC7ED91D2E95C274128" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_DFE773884F1074F834D0D2E95C263118" xlink:to="loc_srt_MajorCustomersAxis_478A045EF7305DC7ED91D2E95C274128" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_478A045EF7305DC7ED91D2E95C274128" xlink:to="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_478A045EF7305DC7ED91D2E95C274128" xlink:to="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_USGovernmentMember" xlink:label="loc_noc_USGovernmentMember_FA243CEEDE355F01F1E9D2E95C27AC4C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300" xlink:to="loc_noc_USGovernmentMember_FA243CEEDE355F01F1E9D2E95C27AC4C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_NonUsMember" xlink:label="loc_us-gaap_NonUsMember_24211DE4B1E5BDEB573BD2E95C2A6C95" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300" xlink:to="loc_us-gaap_NonUsMember_24211DE4B1E5BDEB573BD2E95C2A6C95" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_OtherCustomersMember" xlink:label="loc_noc_OtherCustomersMember_C5676C43A569A978E3E8D2E95C2A3E2C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300" xlink:to="loc_noc_OtherCustomersMember_C5676C43A569A978E3E8D2E95C2A3E2C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_231E032A18196830312CD2E95C2AA07C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_3C70A3A8BA19DADCC26FD2E95C27F300" xlink:to="loc_us-gaap_IntersegmentEliminationMember_231E032A18196830312CD2E95C2AA07C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_690AC1E009EC0446F107D2E95C2AEDCC" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfEntityWideRevenueByMajorCustomersByReportingSegmentsTable_DFE773884F1074F834D0D2E95C263118" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_690AC1E009EC0446F107D2E95C2AEDCC" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_690AC1E009EC0446F107D2E95C2AEDCC" xlink:to="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_690AC1E009EC0446F107D2E95C2AEDCC" xlink:to="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AerospaceSystemsMember" xlink:label="loc_noc_AerospaceSystemsMember_04B3BA1F5DF5716E6229D2E95C2B0A27" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5" xlink:to="loc_noc_AerospaceSystemsMember_04B3BA1F5DF5716E6229D2E95C2B0A27" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_InnovationSystemsMember" xlink:label="loc_noc_InnovationSystemsMember_4244AA0303F82976AF47D2E95C2BA6C9" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5" xlink:to="loc_noc_InnovationSystemsMember_4244AA0303F82976AF47D2E95C2BA6C9" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_MissionSystemsMember" xlink:label="loc_noc_MissionSystemsMember_0BACB788EA04DA16785CD2E95C2B1D68" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5" xlink:to="loc_noc_MissionSystemsMember_0BACB788EA04DA16785CD2E95C2B1D68" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_TechnologyServicesMember" xlink:label="loc_noc_TechnologyServicesMember_6CE87F60BB759861B641D2E95C2B33FE" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_B0EED3220D703A312E61D2E95C2ADEC5" xlink:to="loc_noc_TechnologyServicesMember_6CE87F60BB759861B641D2E95C2B33FE" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_DEFCB18DB2451A3F5C29D2E95C2C40E8" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_2CDB94F6E41F13EA7FCAD2E95C2C8DC1" xlink:to="loc_us-gaap_Revenues_DEFCB18DB2451A3F5C29D2E95C2C40E8" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_33AA3C2A998681B35838D2E95C2CA5D0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EntityWideRevenueMajorCustomerLineItems_2CDB94F6E41F13EA7FCAD2E95C2C8DC1" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_33AA3C2A998681B35838D2E95C2CA5D0" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails3" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems" xlink:label="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_179E771FAEA3CB16EC14D2E95C1FE7BC" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable" xlink:label="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_3FCCF8474EFF6A39EA92D2E95C1B1177" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_179E771FAEA3CB16EC14D2E95C1FE7BC" xlink:to="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_3FCCF8474EFF6A39EA92D2E95C1B1177" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_0160DE6F5309CF95DF53D2E95C1C8CEB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_3FCCF8474EFF6A39EA92D2E95C1B1177" xlink:to="loc_srt_ConsolidationItemsAxis_0160DE6F5309CF95DF53D2E95C1C8CEB" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_7E62489A58A72EEBA1DFD2E95C1C105F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_0160DE6F5309CF95DF53D2E95C1C8CEB" xlink:to="loc_srt_ConsolidationItemsDomain_7E62489A58A72EEBA1DFD2E95C1C105F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_7E62489A58A72EEBA1DFD2E95C1C105F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_0160DE6F5309CF95DF53D2E95C1C8CEB" xlink:to="loc_srt_ConsolidationItemsDomain_7E62489A58A72EEBA1DFD2E95C1C105F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_1F41EE38CCB051F51471D2E95C1CDF09" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_7E62489A58A72EEBA1DFD2E95C1C105F" xlink:to="loc_us-gaap_OperatingSegmentsMember_1F41EE38CCB051F51471D2E95C1CDF09" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingAxis" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_4B35344E915A2CB5D890D2E95C1C036E" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_3FCCF8474EFF6A39EA92D2E95C1B1177" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_4B35344E915A2CB5D890D2E95C1C036E" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_529ACEF10C109782AE8ED2E95C1DF7A9_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_4B35344E915A2CB5D890D2E95C1C036E" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_529ACEF10C109782AE8ED2E95C1DF7A9_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ContractWithCustomerBasisOfPricingDomain" xlink:label="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_529ACEF10C109782AE8ED2E95C1DF7A9" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingAxis_4B35344E915A2CB5D890D2E95C1C036E" xlink:to="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_529ACEF10C109782AE8ED2E95C1DF7A9" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_TimeAndMaterialsContractMember" xlink:label="loc_us-gaap_TimeAndMaterialsContractMember_4C8B88B0611968B72FB9D2E95C1DCAC1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_529ACEF10C109782AE8ED2E95C1DF7A9" xlink:to="loc_us-gaap_TimeAndMaterialsContractMember_4C8B88B0611968B72FB9D2E95C1DCAC1" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_FixedPriceContractMember" xlink:label="loc_us-gaap_FixedPriceContractMember_822947F589806660675CD2E95C1D40A0" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_529ACEF10C109782AE8ED2E95C1DF7A9" xlink:to="loc_us-gaap_FixedPriceContractMember_822947F589806660675CD2E95C1D40A0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_1C51674E50770CF61DB4D2E95C1D4E7C" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ContractWithCustomerBasisOfPricingDomain_529ACEF10C109782AE8ED2E95C1DF7A9" xlink:to="loc_us-gaap_IntersegmentEliminationMember_1C51674E50770CF61DB4D2E95C1D4E7C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_AC43340E98738D5D27DDD2E95C1EE91A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_3FCCF8474EFF6A39EA92D2E95C1B1177" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_AC43340E98738D5D27DDD2E95C1EE91A" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AC43340E98738D5D27DDD2E95C1EE91A" xlink:to="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_AC43340E98738D5D27DDD2E95C1EE91A" xlink:to="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AerospaceSystemsMember" xlink:label="loc_noc_AerospaceSystemsMember_6BB92D7F4B62128C04E8D2E95C1EF9FB" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74" xlink:to="loc_noc_AerospaceSystemsMember_6BB92D7F4B62128C04E8D2E95C1EF9FB" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_InnovationSystemsMember" xlink:label="loc_noc_InnovationSystemsMember_BA7772538836A2F272F7D2E95C1EEEE7" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74" xlink:to="loc_noc_InnovationSystemsMember_BA7772538836A2F272F7D2E95C1EEEE7" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_MissionSystemsMember" xlink:label="loc_noc_MissionSystemsMember_48FD49330B892B685706D2E95C1ECB0A" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74" xlink:to="loc_noc_MissionSystemsMember_48FD49330B892B685706D2E95C1ECB0A" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_TechnologyServicesMember" xlink:label="loc_noc_TechnologyServicesMember_6E86EA2AA4FF9F0F1D86D2E95C1FDD1D" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_3ED5E6F0F65313242746D2E95C1E4F74" xlink:to="loc_noc_TechnologyServicesMember_6E86EA2AA4FF9F0F1D86D2E95C1FDD1D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_4C93BCC878320374C822D2E95C1FD156" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_179E771FAEA3CB16EC14D2E95C1FE7BC" xlink:to="loc_us-gaap_Revenues_4C93BCC878320374C822D2E95C1FD156" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_600B2A5AE14D82B9AE48D2E95C1FE660" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_179E771FAEA3CB16EC14D2E95C1FE7BC" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_600B2A5AE14D82B9AE48D2E95C1FE660" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/SegmentInformationUnauditedDetails4" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_D2E0BF629C51FF713F76D2E95C14EEED" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_2E01F1FB0776344962A8D2E95C0FD122" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_D2E0BF629C51FF713F76D2E95C14EEED" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_2E01F1FB0776344962A8D2E95C0FD122" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsAxis" xlink:label="loc_srt_ConsolidationItemsAxis_BA16EAE8816AF1537B88D2E95C10AA7D" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_2E01F1FB0776344962A8D2E95C0FD122" xlink:to="loc_srt_ConsolidationItemsAxis_BA16EAE8816AF1537B88D2E95C10AA7D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_F39E251569A71465B0DED2E95C103210_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_BA16EAE8816AF1537B88D2E95C10AA7D" xlink:to="loc_srt_ConsolidationItemsDomain_F39E251569A71465B0DED2E95C103210_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_ConsolidationItemsDomain" xlink:label="loc_srt_ConsolidationItemsDomain_F39E251569A71465B0DED2E95C103210" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_BA16EAE8816AF1537B88D2E95C10AA7D" xlink:to="loc_srt_ConsolidationItemsDomain_F39E251569A71465B0DED2E95C103210" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_OperatingSegmentsMember" xlink:label="loc_us-gaap_OperatingSegmentsMember_A6A8A2D8B5241AFC34ABD2E95C1023B7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_F39E251569A71465B0DED2E95C103210" xlink:to="loc_us-gaap_OperatingSegmentsMember_A6A8A2D8B5241AFC34ABD2E95C1023B7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_StatementGeographicalAxis" xlink:label="loc_srt_StatementGeographicalAxis_41E740D4BFD12CA2A07CD2E95C11BE46" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_2E01F1FB0776344962A8D2E95C0FD122" xlink:to="loc_srt_StatementGeographicalAxis_41E740D4BFD12CA2A07CD2E95C11BE46" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_41E740D4BFD12CA2A07CD2E95C11BE46" xlink:to="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_SegmentGeographicalDomain" xlink:label="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_41E740D4BFD12CA2A07CD2E95C11BE46" xlink:to="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E" xlink:type="arc" />
    <link:loc xlink:href="https://xbrl.sec.gov/country/2017/country-2017-01-31.xsd#country_US" xlink:label="loc_country_US_053E00CB54176149C27FD2E95C118997" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E" xlink:to="loc_country_US_053E00CB54176149C27FD2E95C118997" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_AsiaPacificMember" xlink:label="loc_srt_AsiaPacificMember_2E10CD19C260963CBA44D2E95C12D8E1" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E" xlink:to="loc_srt_AsiaPacificMember_2E10CD19C260963CBA44D2E95C12D8E1" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AllOtherGeographicRegionDomain" xlink:label="loc_noc_AllOtherGeographicRegionDomain_A15A8D9DEF64DB5C19D3D2E95C1287A2" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E" xlink:to="loc_noc_AllOtherGeographicRegionDomain_A15A8D9DEF64DB5C19D3D2E95C1287A2" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_IntersegmentEliminationMember" xlink:label="loc_us-gaap_IntersegmentEliminationMember_EDFA60270C14611CC814D2E95C12F2A7" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_0128ED5E5A33FD2899C4D2E95C110D3E" xlink:to="loc_us-gaap_IntersegmentEliminationMember_EDFA60270C14611CC814D2E95C12F2A7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_StatementBusinessSegmentsAxis" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_5E9011CEEDFE1A41005AD2E95C12F25D" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_2E01F1FB0776344962A8D2E95C0FD122" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_5E9011CEEDFE1A41005AD2E95C12F25D" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5E9011CEEDFE1A41005AD2E95C12F25D" xlink:to="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_SegmentDomain" xlink:label="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_5E9011CEEDFE1A41005AD2E95C12F25D" xlink:to="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_AerospaceSystemsMember" xlink:label="loc_noc_AerospaceSystemsMember_C2AFE898A39754F9DDDAD2E95C1335D1" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90" xlink:to="loc_noc_AerospaceSystemsMember_C2AFE898A39754F9DDDAD2E95C1335D1" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_InnovationSystemsMember" xlink:label="loc_noc_InnovationSystemsMember_40B1DE203B90BF595B87D2E95C13E538" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90" xlink:to="loc_noc_InnovationSystemsMember_40B1DE203B90BF595B87D2E95C13E538" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_MissionSystemsMember" xlink:label="loc_noc_MissionSystemsMember_AE75ADEDCCF58CB372A3D2E95C134479" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90" xlink:to="loc_noc_MissionSystemsMember_AE75ADEDCCF58CB372A3D2E95C134479" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_TechnologyServicesMember" xlink:label="loc_noc_TechnologyServicesMember_C8CF23F78F16CB93E0AFD2E95C13B910" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_43E611BBFFF2124EFBBCD2E95C12CB90" xlink:to="loc_noc_TechnologyServicesMember_C8CF23F78F16CB93E0AFD2E95C13B910" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_Revenues" xlink:label="loc_us-gaap_Revenues_215B674CBC2B36EE65AED2E95C147405" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_D2E0BF629C51FF713F76D2E95C14EEED" xlink:to="loc_us-gaap_Revenues_215B674CBC2B36EE65AED2E95C147405" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_DB4849796FC88678770ED2E95C14D4B8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_D2E0BF629C51FF713F76D2E95C14EEED" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_DB4849796FC88678770ED2E95C14D4B8" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/SegmentInformationUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/StockCompensationPlansAndOtherCompensationArrangementsUnaudited" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/StockCompensationPlansAndOtherCompensationArrangementsUnauditedDetails" xlink:type="extended">
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0022E88B53882A85249CD2E95C71748C" xlink:type="locator" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D352A9F10197BBC15F44D2E95C6D4B0A" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0022E88B53882A85249CD2E95C71748C" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D352A9F10197BBC15F44D2E95C6D4B0A" xlink:type="arc" xbrldt:closed="true" xbrldt:contextElement="segment" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaap_AwardTypeAxis_67498D68491DDD5FFEC8D2E95C6D4F6C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D352A9F10197BBC15F44D2E95C6D4B0A" xlink:to="loc_us-gaap_AwardTypeAxis_67498D68491DDD5FFEC8D2E95C6D4F6C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_67498D68491DDD5FFEC8D2E95C6D4F6C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_67498D68491DDD5FFEC8D2E95C6D4F6C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_CC6007854043C801B6DED2E95C6E42B0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_CC6007854043C801B6DED2E95C6E42B0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_PerformanceSharesMember" xlink:label="loc_us-gaap_PerformanceSharesMember_E4EAD03787B9CBAE8FD4D2E95C6E7CC8" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7" xlink:to="loc_us-gaap_PerformanceSharesMember_E4EAD03787B9CBAE8FD4D2E95C6E7CC8" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_CashUnitsMember" xlink:label="loc_noc_CashUnitsMember_B8C96E099EF0FE9749E2D2E95C6E94DB" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7" xlink:to="loc_noc_CashUnitsMember_B8C96E099EF0FE9749E2D2E95C6E94DB" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_CashPerformanceUnitsMember" xlink:label="loc_noc_CashPerformanceUnitsMember_D7DF36CD400C7F94DCEED2E95C6FD58B" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7" xlink:to="loc_noc_CashPerformanceUnitsMember_D7DF36CD400C7F94DCEED2E95C6FD58B" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_CashUnitsAndCashPerformanceUnitsMember" xlink:label="loc_noc_CashUnitsAndCashPerformanceUnitsMember_4A3D5407F548C1EC07F1D2E95C6F4FE3" xlink:type="locator" />
    <link:definitionArc order="5" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_4B01406E4B0FD96537BAD2E95C6E34F7" xlink:to="loc_noc_CashUnitsAndCashPerformanceUnitsMember_4A3D5407F548C1EC07F1D2E95C6F4FE3" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeAxis" xlink:label="loc_srt_RangeAxis_E61B95E621C118273BC3D2E95C6F8D7F" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_D352A9F10197BBC15F44D2E95C6D4B0A" xlink:to="loc_srt_RangeAxis_E61B95E621C118273BC3D2E95C6F8D7F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_2295A2B7A40774038796D2E95C6F466F_default" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_E61B95E621C118273BC3D2E95C6F8D7F" xlink:to="loc_srt_RangeMember_2295A2B7A40774038796D2E95C6F466F_default" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_RangeMember" xlink:label="loc_srt_RangeMember_2295A2B7A40774038796D2E95C6F466F" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_E61B95E621C118273BC3D2E95C6F8D7F" xlink:to="loc_srt_RangeMember_2295A2B7A40774038796D2E95C6F466F" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MinimumMember" xlink:label="loc_srt_MinimumMember_64D68E10A829D18405FFD2E95C70080C" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_2295A2B7A40774038796D2E95C6F466F" xlink:to="loc_srt_MinimumMember_64D68E10A829D18405FFD2E95C70080C" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/srt/2019/elts/srt-2019-01-31.xsd#srt_MaximumMember" xlink:label="loc_srt_MaximumMember_0FD622C2B7CCC3C17DC1D2E95C715A54" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_2295A2B7A40774038796D2E95C6F466F" xlink:to="loc_srt_MaximumMember_0FD622C2B7CCC3C17DC1D2E95C715A54" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_DeferredCompensationCashbasedArrangementsLiabilityCurrentAndNoncurrent" xlink:label="loc_us-gaap_DeferredCompensationCashbasedArrangementsLiabilityCurrentAndNoncurrent_98EEB713B917B861E911D2E95C71C9F0" xlink:type="locator" />
    <link:definitionArc order="1" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0022E88B53882A85249CD2E95C71748C" xlink:to="loc_us-gaap_DeferredCompensationCashbasedArrangementsLiabilityCurrentAndNoncurrent_98EEB713B917B861E911D2E95C71C9F0" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_7606D015E212C24E35A2D2E95C71B495" xlink:type="locator" />
    <link:definitionArc order="2" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0022E88B53882A85249CD2E95C71748C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_7606D015E212C24E35A2D2E95C71B495" xlink:type="arc" />
    <link:loc xlink:href="http://xbrl.fasb.org/us-gaap/2019/elts/us-gaap-2019-01-31.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_2B626BC302B899E52273D2E95C717B83" xlink:type="locator" />
    <link:definitionArc order="3" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0022E88B53882A85249CD2E95C71748C" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_2B626BC302B899E52273D2E95C717B83" xlink:type="arc" />
    <link:loc xlink:href="noc-20190630.xsd#noc_RestrictedStockRightsandRestrictedPerformanceStockRightsGrantDateAggregateFairValue" xlink:label="loc_noc_RestrictedStockRightsandRestrictedPerformanceStockRightsGrantDateAggregateFairValue_C030D78556C9729733E3D2E95C71E53C" xlink:type="locator" />
    <link:definitionArc order="4" xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_0022E88B53882A85249CD2E95C71748C" xlink:to="loc_noc_RestrictedStockRightsandRestrictedPerformanceStockRightsGrantDateAggregateFairValue_C030D78556C9729733E3D2E95C71E53C" xlink:type="arc" />
  </link:definitionLink>
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/StockCompensationPlansAndOtherCompensationArrangementsUnauditedTables" xlink:type="extended" />
  <link:definitionLink xlink:role="http://www.northropgrumman.com/role/SummaryOfSignificantAccountingPoliciesPolicies" xlink:type="extended" />
</link:linkbase>
