<?xml version="1.0" encoding="US-ASCII" standalone="no"?>
    <!-- Field: Doc-Info; Name: Generator; Value: GoFiler Complete; Version: 6.5a -->
    <!-- Field: Doc-Info; Name: VendorURI; Value: https://www.novaworks.com -->
    <!-- Field: Doc-Info; Name: Status; Value: 0x00000000 -->
<link:linkbase xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xmlns:xbrli="http://www.xbrl.org/2003/instance" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#Cover" roleURI="http://trulitechnologies.com/role/Cover" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#BalanceSheets" roleURI="http://trulitechnologies.com/role/BalanceSheets" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#BalanceSheetsParenthetical" roleURI="http://trulitechnologies.com/role/BalanceSheetsParenthetical" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#StatementsOfOperations" roleURI="http://trulitechnologies.com/role/StatementsOfOperations" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#StatementOfChangesInStockholdersEquity" roleURI="http://trulitechnologies.com/role/StatementOfChangesInStockholdersEquity" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#StatementsOfCashFlows" roleURI="http://trulitechnologies.com/role/StatementsOfCashFlows" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#OrganizationAndSummaryOfSignificantAccountingPolicies" roleURI="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#GoingConcern" roleURI="http://trulitechnologies.com/role/GoingConcern" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#PrepaidExpensesAndOtherCurrentAssets" roleURI="http://trulitechnologies.com/role/PrepaidExpensesAndOtherCurrentAssets" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#InvestmentInAvailableForSaleMarketableSecurities" roleURI="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecurities" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#GoodwillAndOtherIntangibleAssets" roleURI="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssets" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#DiscontinuedOperations" roleURI="http://trulitechnologies.com/role/DiscontinuedOperations" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#LoansPayableAndFinancingAgreements" roleURI="http://trulitechnologies.com/role/LoansPayableAndFinancingAgreements" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#StockholdersEquity" roleURI="http://trulitechnologies.com/role/StockholdersEquity" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#StockOptionsAndWarrants" roleURI="http://trulitechnologies.com/role/StockOptionsAndWarrants" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#CommitmentsAndContingencies" roleURI="http://trulitechnologies.com/role/CommitmentsAndContingencies" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#RelatedPartyTransactions" roleURI="http://trulitechnologies.com/role/RelatedPartyTransactions" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#SegmentReporting" roleURI="http://trulitechnologies.com/role/SegmentReporting" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#SubsequentEvents" roleURI="http://trulitechnologies.com/role/SubsequentEvents" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#OrganizationAndSummaryOfSignificantAccountingPoliciesPolicies" roleURI="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesPolicies" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#OrganizationAndSummaryOfSignificantAccountingPoliciesTables" roleURI="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesTables" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#PrepaidExpensesAndOtherCurrentAssetsTables" roleURI="http://trulitechnologies.com/role/PrepaidExpensesAndOtherCurrentAssetsTables" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#InvestmentInAvailableForSaleMarketableSecuritiesTables" roleURI="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecuritiesTables" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#GoodwillAndOtherIntangibleAssetsTables" roleURI="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssetsTables" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#DiscontinuedOperationsTables" roleURI="http://trulitechnologies.com/role/DiscontinuedOperationsTables" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#SegmentReportingTables" roleURI="http://trulitechnologies.com/role/SegmentReportingTables" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-RevenueDisaggregation" roleURI="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-RevenueDisaggregation" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-FinancialAssetsAndLiabilities" roleURI="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-FinancialAssetsAndLiabilities" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-NetIncome" roleURI="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-NetIncome" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#OrganizationAndSummaryOfSignificantAccountingPoliciesDetailsNarrative" roleURI="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#GoingConcernDetailsNarrative" roleURI="http://trulitechnologies.com/role/GoingConcernDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#PrepaidExpensesAndOtherCurrentAssetsDetails-PrepaidExpenses" roleURI="http://trulitechnologies.com/role/PrepaidExpensesAndOtherCurrentAssetsDetails-PrepaidExpenses" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#InvestmentInAvailableForSaleMarketableSecuritiesDetails-InvestmentInMarketableSecurities" roleURI="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecuritiesDetails-InvestmentInMarketableSecurities" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#InvestmentInAvailableForSaleMarketableSecuritiesDetailsNarrative" roleURI="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecuritiesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#GoodwillAndOtherIntangibleAssetsDetails-IntangibleAssets" roleURI="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssetsDetails-IntangibleAssets" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#GoodwillAndOtherIntangibleAssetsDetailsNarrative" roleURI="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssetsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#DiscontinuedOperationsDetails-NetLossFromDiscontinuedOperation" roleURI="http://trulitechnologies.com/role/DiscontinuedOperationsDetails-NetLossFromDiscontinuedOperation" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#LoansPayableAndFinancingAgreementsDetailsNarrative" roleURI="http://trulitechnologies.com/role/LoansPayableAndFinancingAgreementsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#StockholdersEquityDetailsNarrative" roleURI="http://trulitechnologies.com/role/StockholdersEquityDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#StockOptionsAndWarrantsDetailsNarrative" roleURI="http://trulitechnologies.com/role/StockOptionsAndWarrantsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#CommitmentsAndContingenciesDetailsNarrative" roleURI="http://trulitechnologies.com/role/CommitmentsAndContingenciesDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#RelatedPartyTransactionsDetailsNarrative" roleURI="http://trulitechnologies.com/role/RelatedPartyTransactionsDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#SegmentReportingDetails-SegmentInformation" roleURI="http://trulitechnologies.com/role/SegmentReportingDetails-SegmentInformation" />
    <link:roleRef xlink:type="simple" xlink:href="nixx-20260331.xsd#SegmentReportingDetailsNarrative" roleURI="http://trulitechnologies.com/role/SegmentReportingDetailsNarrative" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#PvpExecutiveCategoriesOnly" roleURI="http://xbrl.sec.gov/ecd/role/PvpExecutiveCategoriesOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#PvpAdjustmentsOnly" roleURI="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#IndividualsOnly" roleURI="http://xbrl.sec.gov/ecd/role/IndividualsOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#AwardTypeOnly" roleURI="http://xbrl.sec.gov/ecd/AwardTypeOnly" />
    <link:roleRef xlink:type="simple" xlink:href="https://xbrl.sec.gov/ecd/2026/ecd-2026.xsd#TradingArrangmentsOnly" roleURI="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension" arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member" arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all" arcroleURI="http://xbrl.org/int/dim/arcrole/all" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#notAll" arcroleURI="http://xbrl.org/int/dim/arcrole/notAll" />
    <link:arcroleRef xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default" arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/Cover" xlink:title="00000001 - Document - Cover">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapCommonStockMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_CommonStockPurchaseWarrantsMember" xlink:label="loc_NIXXCommonStockPurchaseWarrantsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_NIXXCommonStockPurchaseWarrantsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentType" xlink:label="loc_deiDocumentType_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentType_50" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentFlag" xlink:label="loc_deiAmendmentFlag_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiAmendmentFlag_50" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AmendmentDescription" xlink:label="loc_deiAmendmentDescription_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiAmendmentDescription_50" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentRegistrationStatement" xlink:label="loc_deiDocumentRegistrationStatement_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentRegistrationStatement_50" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentAnnualReport" xlink:label="loc_deiDocumentAnnualReport_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentAnnualReport_50" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentQuarterlyReport" xlink:label="loc_deiDocumentQuarterlyReport_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentQuarterlyReport_50" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentTransitionReport" xlink:label="loc_deiDocumentTransitionReport_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentTransitionReport_50" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentShellCompanyReport" xlink:label="loc_deiDocumentShellCompanyReport_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentShellCompanyReport_50" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentShellCompanyEventDate" xlink:label="loc_deiDocumentShellCompanyEventDate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentShellCompanyEventDate_50" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodStartDate" xlink:label="loc_deiDocumentPeriodStartDate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentPeriodStartDate_50" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentPeriodEndDate" xlink:label="loc_deiDocumentPeriodEndDate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentPeriodEndDate_50" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalPeriodFocus" xlink:label="loc_deiDocumentFiscalPeriodFocus_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentFiscalPeriodFocus_50" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentFiscalYearFocus" xlink:label="loc_deiDocumentFiscalYearFocus_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentFiscalYearFocus_50" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CurrentFiscalYearEndDate" xlink:label="loc_deiCurrentFiscalYearEndDate_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiCurrentFiscalYearEndDate_50" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFileNumber" xlink:label="loc_deiEntityFileNumber_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityFileNumber_50" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityRegistrantName" xlink:label="loc_deiEntityRegistrantName_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityRegistrantName_50" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCentralIndexKey" xlink:label="loc_deiEntityCentralIndexKey_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityCentralIndexKey_50" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityPrimarySicNumber" xlink:label="loc_deiEntityPrimarySicNumber_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityPrimarySicNumber_50" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityTaxIdentificationNumber" xlink:label="loc_deiEntityTaxIdentificationNumber_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityTaxIdentificationNumber_50" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityIncorporationStateCountryCode" xlink:label="loc_deiEntityIncorporationStateCountryCode_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityIncorporationStateCountryCode_50" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine1" xlink:label="loc_deiEntityAddressAddressLine1_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityAddressAddressLine1_50" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine2" xlink:label="loc_deiEntityAddressAddressLine2_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityAddressAddressLine2_50" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressAddressLine3" xlink:label="loc_deiEntityAddressAddressLine3_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityAddressAddressLine3_50" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCityOrTown" xlink:label="loc_deiEntityAddressCityOrTown_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityAddressCityOrTown_50" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressStateOrProvince" xlink:label="loc_deiEntityAddressStateOrProvince_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityAddressStateOrProvince_50" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressCountry" xlink:label="loc_deiEntityAddressCountry_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityAddressCountry_50" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityAddressPostalZipCode" xlink:label="loc_deiEntityAddressPostalZipCode_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityAddressPostalZipCode_50" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CountryRegion" xlink:label="loc_deiCountryRegion_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiCountryRegion_50" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_CityAreaCode" xlink:label="loc_deiCityAreaCode_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiCityAreaCode_50" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LocalPhoneNumber" xlink:label="loc_deiLocalPhoneNumber_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiLocalPhoneNumber_50" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Extension" xlink:label="loc_deiExtension_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiExtension_50" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_WrittenCommunications" xlink:label="loc_deiWrittenCommunications_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiWrittenCommunications_50" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SolicitingMaterial" xlink:label="loc_deiSolicitingMaterial_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiSolicitingMaterial_50" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementTenderOffer" xlink:label="loc_deiPreCommencementTenderOffer_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiPreCommencementTenderOffer_50" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_PreCommencementIssuerTenderOffer" xlink:label="loc_deiPreCommencementIssuerTenderOffer_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiPreCommencementIssuerTenderOffer_50" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12bTitle" xlink:label="loc_deiSecurity12bTitle_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiSecurity12bTitle_50" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_NoTradingSymbolFlag" xlink:label="loc_deiNoTradingSymbolFlag_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiNoTradingSymbolFlag_50" xlink:type="arc" order="36" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_TradingSymbol" xlink:label="loc_deiTradingSymbol_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiTradingSymbol_50" xlink:type="arc" order="37" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityExchangeName" xlink:label="loc_deiSecurityExchangeName_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiSecurityExchangeName_50" xlink:type="arc" order="38" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_Security12gTitle" xlink:label="loc_deiSecurity12gTitle_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiSecurity12gTitle_50" xlink:type="arc" order="39" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_SecurityReportingObligation" xlink:label="loc_deiSecurityReportingObligation_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiSecurityReportingObligation_50" xlink:type="arc" order="40" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AnnualInformationForm" xlink:label="loc_deiAnnualInformationForm_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiAnnualInformationForm_50" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_AuditedAnnualFinancialStatements" xlink:label="loc_deiAuditedAnnualFinancialStatements_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiAuditedAnnualFinancialStatements_50" xlink:type="arc" order="42" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityWellKnownSeasonedIssuer" xlink:label="loc_deiEntityWellKnownSeasonedIssuer_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityWellKnownSeasonedIssuer_50" xlink:type="arc" order="43" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityVoluntaryFilers" xlink:label="loc_deiEntityVoluntaryFilers_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityVoluntaryFilers_50" xlink:type="arc" order="44" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCurrentReportingStatus" xlink:label="loc_deiEntityCurrentReportingStatus_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityCurrentReportingStatus_50" xlink:type="arc" order="45" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityInteractiveDataCurrent" xlink:label="loc_deiEntityInteractiveDataCurrent_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityInteractiveDataCurrent_50" xlink:type="arc" order="46" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityFilerCategory" xlink:label="loc_deiEntityFilerCategory_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityFilerCategory_50" xlink:type="arc" order="47" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntitySmallBusiness" xlink:label="loc_deiEntitySmallBusiness_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntitySmallBusiness_50" xlink:type="arc" order="48" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityEmergingGrowthCompany" xlink:label="loc_deiEntityEmergingGrowthCompany_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityEmergingGrowthCompany_50" xlink:type="arc" order="49" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityExTransitionPeriod" xlink:label="loc_deiEntityExTransitionPeriod_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityExTransitionPeriod_50" xlink:type="arc" order="50" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentAccountingStandard" xlink:label="loc_deiDocumentAccountingStandard_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentAccountingStandard_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_OtherReportingStandardItemNumber" xlink:label="loc_deiOtherReportingStandardItemNumber_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiOtherReportingStandardItemNumber_50" xlink:type="arc" order="52" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityShellCompany" xlink:label="loc_deiEntityShellCompany_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityShellCompany_50" xlink:type="arc" order="53" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityPublicFloat" xlink:label="loc_deiEntityPublicFloat_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityPublicFloat_50" xlink:type="arc" order="54" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityBankruptcyProceedingsReportingCurrent" xlink:label="loc_deiEntityBankruptcyProceedingsReportingCurrent_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityBankruptcyProceedingsReportingCurrent_50" xlink:type="arc" order="55" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityCommonStockSharesOutstanding" xlink:label="loc_deiEntityCommonStockSharesOutstanding_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiEntityCommonStockSharesOutstanding_50" xlink:type="arc" order="56" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_DocumentsIncorporatedByReferenceTextBlock" xlink:label="loc_deiDocumentsIncorporatedByReferenceTextBlock_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_deiDocumentsIncorporatedByReferenceTextBlock_50" xlink:type="arc" order="57" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/BalanceSheets" xlink:title="00000002 - Statement - Condensed Consolidated Balance Sheets" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/BalanceSheetsParenthetical" xlink:title="00000003 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/StatementsOfOperations" xlink:title="00000004 - Statement - Condensed Consolidated Statements of Operations (Unaudited)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/StatementOfChangesInStockholdersEquity" xlink:title="00000005 - Statement - Condensed Consolidated Statement of Changes in Stockholders&apos; Equity (Unaudited)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems" xlink:label="loc_us-gaapStatementLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable" xlink:label="loc_us-gaapStatementTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStatementTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis" xlink:label="loc_us-gaapStatementEquityComponentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapStatementTable" xlink:to="loc_us-gaapStatementEquityComponentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain" xlink:label="loc_us-gaapEquityComponentDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementEquityComponentsAxis" xlink:to="loc_us-gaapEquityComponentDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapCommonStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_CommonStockToBeIssuedMember" xlink:label="loc_NIXXCommonStockToBeIssuedMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_NIXXCommonStockToBeIssuedMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember" xlink:label="loc_us-gaapAdditionalPaidInCapitalMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapAdditionalPaidInCapitalMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember" xlink:label="loc_us-gaapRetainedEarningsMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapRetainedEarningsMember_30" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncontrollingInterestMember" xlink:label="loc_us-gaapNoncontrollingInterestMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapEquityComponentDomain" xlink:to="loc_us-gaapNoncontrollingInterestMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest" xlink:label="loc_us-gaapStockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_70" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesOutstanding" xlink:label="loc_us-gaapSharesOutstanding_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapSharesOutstanding_70" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition" xlink:label="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapAdjustmentsToAdditionalPaidInCapitalShareBasedCompensationStockOptionsRequisiteServicePeriodRecognition_70" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_70" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_70" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_StockIssuedDuringPeriodValueSettlementOfDebt" xlink:label="loc_NIXXStockIssuedDuringPeriodValueSettlementOfDebt_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_NIXXStockIssuedDuringPeriodValueSettlementOfDebt_70" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_StockIssuedDuringPeriodSharesSettlementOfDebt" xlink:label="loc_NIXXStockIssuedDuringPeriodSharesSettlementOfDebt_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_NIXXStockIssuedDuringPeriodSharesSettlementOfDebt_70" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_70" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_70" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueOther_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueOther_70" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesOther_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesOther_70" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValuePurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_70" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesPurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_70" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss" xlink:label="loc_us-gaapNetIncomeLoss_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapStatementLineItems" xlink:to="loc_us-gaapNetIncomeLoss_70" xlink:type="arc" order="14" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/StatementsOfCashFlows" xlink:title="00000006 - Statement - Condensed Consolidated Statements of Cash Flows (Unaudited)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPolicies" xlink:title="999012 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/GoingConcern" xlink:title="999013 - Disclosure - GOING CONCERN" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/PrepaidExpensesAndOtherCurrentAssets" xlink:title="999014 - Disclosure - PREPAID EXPENSES AND OTHER CURRENT ASSETS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecurities" xlink:title="999015 - Disclosure - INVESTMENT IN AVAILABLE FOR SALE MARKETABLE SECURITIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssets" xlink:title="999016 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/DiscontinuedOperations" xlink:title="999017 - Disclosure - DISCONTINUED OPERATIONS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/LoansPayableAndFinancingAgreements" xlink:title="999018 - Disclosure - LOANS PAYABLE AND FINANCING AGREEMENTS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/StockholdersEquity" xlink:title="999019 - Disclosure - STOCKHOLDERS&#8217; EQUITY" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/StockOptionsAndWarrants" xlink:title="999020 - Disclosure - STOCK OPTIONS AND WARRANTS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/CommitmentsAndContingencies" xlink:title="999021 - Disclosure - COMMITMENTS AND CONTINGENCIES" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/RelatedPartyTransactions" xlink:title="999022 - Disclosure - RELATED PARTY TRANSACTIONS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/SegmentReporting" xlink:title="999023 - Disclosure - SEGMENT REPORTING" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/SubsequentEvents" xlink:title="999024 - Disclosure - SUBSEQUENT EVENTS" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesPolicies" xlink:title="999025 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesTables" xlink:title="999026 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/PrepaidExpensesAndOtherCurrentAssetsTables" xlink:title="999027 - Disclosure - PREPAID EXPENSES AND OTHER CURRENT ASSETS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecuritiesTables" xlink:title="999028 - Disclosure - INVESTMENT IN AVAILABLE FOR SALE MARKETABLE SECURITIES (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssetsTables" xlink:title="999029 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/DiscontinuedOperationsTables" xlink:title="999030 - Disclosure - DISCONTINUED OPERATIONS (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/SegmentReportingTables" xlink:title="999031 - Disclosure - SEGMENT REPORTING (Tables)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-RevenueDisaggregation" xlink:title="999032 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details - Revenue disaggregation)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:label="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:label="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis" xlink:label="loc_srtProductOrServiceAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable" xlink:to="loc_srtProductOrServiceAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srtProductsAndServicesDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtProductOrServiceAxis" xlink:to="loc_srtProductsAndServicesDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain" xlink:label="loc_srtProductsAndServicesDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtProductOrServiceAxis" xlink:to="loc_srtProductsAndServicesDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_TelecommunicationServicesMember" xlink:label="loc_NIXXTelecommunicationServicesMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtProductsAndServicesDomain" xlink:to="loc_NIXXTelecommunicationServicesMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues" xlink:label="loc_us-gaapRevenues_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems" xlink:to="loc_us-gaapRevenues_50" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-FinancialAssetsAndLiabilities" xlink:title="999033 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details - Financial assets and liabilities)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:label="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" xlink:label="loc_us-gaapDebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapDebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FinancialInstrumentAxis" xlink:label="loc_us-gaapFinancialInstrumentAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" xlink:to="loc_us-gaapFinancialInstrumentAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:label="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFinancialInstrumentAxis" xlink:to="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_MarketableSecuritiesMember" xlink:label="loc_NIXXMarketableSecuritiesMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain" xlink:to="loc_NIXXMarketableSecuritiesMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis" xlink:label="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapDebtSecuritiesHeldToMaturityAllowanceForCreditLossTable" xlink:to="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain" xlink:label="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFairValueByFairValueHierarchyLevelAxis" xlink:to="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member" xlink:label="loc_us-gaapFairValueInputsLevel1Member_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel1Member_10" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member" xlink:label="loc_us-gaapFairValueInputsLevel2Member_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel2Member_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member" xlink:label="loc_us-gaapFairValueInputsLevel3Member_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFairValueMeasurementsFairValueHierarchyDomain" xlink:to="loc_us-gaapFairValueInputsLevel3Member_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetsFairValueDisclosure" xlink:label="loc_us-gaapAssetsFairValueDisclosure_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDebtSecuritiesHeldtomaturityAllowanceForCreditLossLineItems" xlink:to="loc_us-gaapAssetsFairValueDisclosure_90" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetails-NetIncome" xlink:title="999034 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details - Net income)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_OptionsMember" xlink:label="loc_NIXXOptionsMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_NIXXOptionsMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsMember" xlink:label="loc_NIXXWarrantsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_NIXXWarrantsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic" xlink:label="loc_us-gaapNetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapNetIncomeLossFromContinuingOperationsAvailableToCommonShareholdersBasic_70" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount" xlink:label="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_70" xlink:type="arc" order="1" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/OrganizationAndSummaryOfSignificantAccountingPoliciesDetailsNarrative" xlink:title="999035 - Disclosure - ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductInformationLineItems" xlink:label="loc_us-gaapProductInformationLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfProductInformationTable" xlink:label="loc_us-gaapScheduleOfProductInformationTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapScheduleOfProductInformationTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis" xlink:label="loc_us-gaapConcentrationRiskByBenchmarkAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfProductInformationTable" xlink:to="loc_us-gaapConcentrationRiskByBenchmarkAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaapConcentrationRiskBenchmarkDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapConcentrationRiskByBenchmarkAxis" xlink:to="loc_us-gaapConcentrationRiskBenchmarkDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain" xlink:label="loc_us-gaapConcentrationRiskBenchmarkDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapConcentrationRiskByBenchmarkAxis" xlink:to="loc_us-gaapConcentrationRiskBenchmarkDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SalesRevenueNetMember" xlink:label="loc_us-gaapSalesRevenueNetMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskBenchmarkDomain" xlink:to="loc_us-gaapSalesRevenueNetMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccountsReceivableMember" xlink:label="loc_us-gaapAccountsReceivableMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskBenchmarkDomain" xlink:to="loc_us-gaapAccountsReceivableMember_60" xlink:type="arc" order="62" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis" xlink:label="loc_us-gaapConcentrationRiskByTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfProductInformationTable" xlink:to="loc_us-gaapConcentrationRiskByTypeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaapConcentrationRiskTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapConcentrationRiskByTypeAxis" xlink:to="loc_us-gaapConcentrationRiskTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain" xlink:label="loc_us-gaapConcentrationRiskTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapConcentrationRiskByTypeAxis" xlink:to="loc_us-gaapConcentrationRiskTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember" xlink:label="loc_us-gaapCustomerConcentrationRiskMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapConcentrationRiskTypeDomain" xlink:to="loc_us-gaapCustomerConcentrationRiskMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis" xlink:label="loc_srtMajorCustomersAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfProductInformationTable" xlink:to="loc_srtMajorCustomersAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srtNameOfMajorCustomerDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtMajorCustomersAxis" xlink:to="loc_srtNameOfMajorCustomerDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain" xlink:label="loc_srtNameOfMajorCustomerDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtMajorCustomersAxis" xlink:to="loc_srtNameOfMajorCustomerDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_InternationalSourcesMember" xlink:label="loc_NIXXInternationalSourcesMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_NIXXInternationalSourcesMember_20" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ThreeCustomersMember" xlink:label="loc_NIXXThreeCustomersMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_NIXXThreeCustomersMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_FourCustomersMember" xlink:label="loc_NIXXFourCustomersMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_NIXXFourCustomersMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_TwoCustomersMember" xlink:label="loc_NIXXTwoCustomersMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtNameOfMajorCustomerDomain" xlink:to="loc_NIXXTwoCustomersMember_90" xlink:type="arc" order="91" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashUninsuredAmount" xlink:label="loc_us-gaapCashUninsuredAmount_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapCashUninsuredAmount_110" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashEquivalentsAtCarryingValue" xlink:label="loc_us-gaapCashEquivalentsAtCarryingValue_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapCashEquivalentsAtCarryingValue_110" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1" xlink:label="loc_us-gaapConcentrationRiskPercentage1_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapConcentrationRiskPercentage1_110" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllowanceForDoubtfulAccountsReceivableCurrent" xlink:label="loc_us-gaapAllowanceForDoubtfulAccountsReceivableCurrent_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapAllowanceForDoubtfulAccountsReceivableCurrent_110" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_CreditLossExpense" xlink:label="loc_NIXXCreditLossExpense_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_NIXXCreditLossExpense_110" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Depreciation" xlink:label="loc_us-gaapDepreciation_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapDepreciation_110" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketingAndAdvertisingExpense" xlink:label="loc_us-gaapMarketingAndAdvertisingExpense_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapMarketingAndAdvertisingExpense_110" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments" xlink:label="loc_us-gaapNumberOfReportableSegments_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapNumberOfReportableSegments_110" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfOperatingSegments" xlink:label="loc_us-gaapNumberOfOperatingSegments_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapProductInformationLineItems" xlink:to="loc_us-gaapNumberOfOperatingSegments_110" xlink:type="arc" order="8" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/GoingConcernDetailsNarrative" xlink:title="999036 - Disclosure - GOING CONCERN (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/PrepaidExpensesAndOtherCurrentAssetsDetails-PrepaidExpenses" xlink:title="999037 - Disclosure - PREPAID EXPENSES AND OTHER CURRENT ASSETS (Details - Prepaid expenses)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecuritiesDetails-InvestmentInMarketableSecurities" xlink:title="999038 - Disclosure - INVESTMENT IN AVAILABLE FOR SALE MARKETABLE SECURITIES (Details - Investment in marketable securities)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/InvestmentInAvailableForSaleMarketableSecuritiesDetailsNarrative" xlink:title="999039 - Disclosure - INVESTMENT IN AVAILABLE FOR SALE MARKETABLE SECURITIES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketableSecuritiesLineItems" xlink:label="loc_us-gaapMarketableSecuritiesLineItems" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisclosureTable" xlink:label="loc_NIXXDisclosureTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_NIXXDisclosureTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:label="loc_srtScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_NIXXDisclosureTable" xlink:to="loc_srtScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="loc_srtEquityMethodInvesteeNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="loc_srtEquityMethodInvesteeNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_EquityMethodInvesteeNameDomain" xlink:label="loc_srtEquityMethodInvesteeNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis" xlink:to="loc_srtEquityMethodInvesteeNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_CognoGroupIncMember" xlink:label="loc_NIXXCognoGroupIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtEquityMethodInvesteeNameDomain" xlink:to="loc_NIXXCognoGroupIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityMethodInvestmentOwnershipPercentage" xlink:label="loc_us-gaapEquityMethodInvestmentOwnershipPercentage_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapEquityMethodInvestmentOwnershipPercentage_60" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentOwnedBalanceShares" xlink:label="loc_us-gaapInvestmentOwnedBalanceShares_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapInvestmentOwnedBalanceShares_60" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueAcquisitions_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueAcquisitions_60" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities" xlink:label="loc_us-gaapAvailableForSaleSecuritiesDebtSecurities_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapAvailableForSaleSecuritiesDebtSecurities_60" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainLossBeforeTax" xlink:label="loc_us-gaapDebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainLossBeforeTax_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapDebtSecuritiesAvailableForSaleAccumulatedGrossUnrealizedGainLossBeforeTax_60" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MarketableSecuritiesCurrent" xlink:label="loc_us-gaapMarketableSecuritiesCurrent_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapMarketableSecuritiesCurrent_60" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RealizedInvestmentGainsLosses" xlink:label="loc_us-gaapRealizedInvestmentGainsLosses_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapRealizedInvestmentGainsLosses_60" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnInvestments" xlink:label="loc_us-gaapUnrealizedGainLossOnInvestments_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapMarketableSecuritiesLineItems" xlink:to="loc_us-gaapUnrealizedGainLossOnInvestments_60" xlink:type="arc" order="7" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssetsDetails-IntangibleAssets" xlink:title="999040 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Details - Intangible assets)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerContractsMember" xlink:label="loc_us-gaapCustomerContractsMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapCustomerContractsMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_AcquiredSoftwareMember" xlink:label="loc_NIXXAcquiredSoftwareMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_NIXXAcquiredSoftwareMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DomainsMember" xlink:label="loc_NIXXDomainsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_NIXXDomainsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LicenseMember" xlink:label="loc_us-gaapLicenseMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapLicenseMember_60" xlink:type="arc" order="61" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SoftwareDevelopmentMember" xlink:label="loc_us-gaapSoftwareDevelopmentMember_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_us-gaapSoftwareDevelopmentMember_80" xlink:type="arc" order="81" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsGross_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsGross_130" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_AccumulatedImpairmentOfIntangibleAssetsFinitelived" xlink:label="loc_NIXXAccumulatedImpairmentOfIntangibleAssetsFinitelived_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_NIXXAccumulatedImpairmentOfIntangibleAssetsFinitelived_130" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_130" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsNet_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsNet_130" xlink:type="arc" order="3" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/GoodwillAndOtherIntangibleAssetsDetailsNarrative" xlink:title="999041 - Disclosure - GOODWILL AND OTHER INTANGIBLE ASSETS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable" xlink:label="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis" xlink:label="loc_srtCounterpartyNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_srtCounterpartyNameAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srtRepurchaseAgreementCounterpartyNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtCounterpartyNameAxis" xlink:to="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srtRepurchaseAgreementCounterpartyNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtCounterpartyNameAxis" xlink:to="loc_srtRepurchaseAgreementCounterpartyNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_GOLQMember" xlink:label="loc_NIXXGOLQMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXGOLQMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis" xlink:label="loc_us-gaapAssetAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_us-gaapAssetAcquisitionAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain" xlink:label="loc_us-gaapAssetAcquisitionDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAssetAcquisitionAxis" xlink:to="loc_us-gaapAssetAcquisitionDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain" xlink:label="loc_us-gaapAssetAcquisitionDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAssetAcquisitionAxis" xlink:to="loc_us-gaapAssetAcquisitionDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SavitrTechOUMember" xlink:label="loc_NIXXSavitrTechOUMember_70" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXSavitrTechOUMember_70" xlink:type="arc" order="71" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_AquaSoftwareTechnologiesMember" xlink:label="loc_NIXXAquaSoftwareTechnologiesMember_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXAquaSoftwareTechnologiesMember_130" xlink:type="arc" order="131" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_NexGenAIAPAMember" xlink:label="loc_NIXXNexGenAIAPAMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXNexGenAIAPAMember_150" xlink:type="arc" order="151" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EverythinkAssetAcquisitionMember" xlink:label="loc_NIXXEverythinkAssetAcquisitionMember_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_NIXXEverythinkAssetAcquisitionMember_210" xlink:type="arc" order="211" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfFiniteLivedIntangibleAssetsTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EverythingAssetsMember" xlink:label="loc_NIXXEverythingAssetsMember_220" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_NIXXEverythingAssetsMember_220" xlink:type="arc" order="221" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DomainsMember" xlink:label="loc_NIXXDomainsMember_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_NIXXDomainsMember_250" xlink:type="arc" order="251" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLossNetOfTax" xlink:label="loc_us-gaapGoodwillImpairmentLossNetOfTax_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapGoodwillImpairmentLossNetOfTax_270" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill" xlink:label="loc_us-gaapGoodwill_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapGoodwill_270" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesPurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_270" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValuePurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_270" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsIssuedShares" xlink:label="loc_NIXXWarrantsIssuedShares_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_NIXXWarrantsIssuedShares_270" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WarrantsAndRightsOutstanding" xlink:label="loc_us-gaapWarrantsAndRightsOutstanding_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapWarrantsAndRightsOutstanding_270" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsGross_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsGross_270" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_270" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsNet_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsNet_270" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionConsiderationTransferred" xlink:label="loc_us-gaapAssetAcquisitionConsiderationTransferred_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapAssetAcquisitionConsiderationTransferred_270" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireProductiveAssets" xlink:label="loc_us-gaapPaymentsToAcquireProductiveAssets_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapPaymentsToAcquireProductiveAssets_270" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionContingentConsiderationLiability" xlink:label="loc_us-gaapAssetAcquisitionContingentConsiderationLiability_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapAssetAcquisitionContingentConsiderationLiability_270" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ChangeInFairValueOfContingentConsideration" xlink:label="loc_NIXXChangeInFairValueOfContingentConsideration_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_NIXXChangeInFairValueOfContingentConsideration_270" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetUsefulLife_270" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsToAcquireBusinessesGross" xlink:label="loc_us-gaapPaymentsToAcquireBusinessesGross_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapPaymentsToAcquireBusinessesGross_270" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_270" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextRollingTwelveMonths" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseNextRollingTwelveMonths_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseNextRollingTwelveMonths_270" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseRemainderOfFiscalYear_270" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths_270" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseYearTwo_270" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseYearThree_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseYearThree_270" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseYearFour_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAmortizationExpenseYearFour_270" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetImpairmentCharges" xlink:label="loc_us-gaapAssetImpairmentCharges_270" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsLineItems" xlink:to="loc_us-gaapAssetImpairmentCharges_270" xlink:type="arc" order="22" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/DiscontinuedOperationsDetails-NetLossFromDiscontinuedOperation" xlink:title="999042 - Disclosure - DISCONTINUED OPERATIONS (Details - Net loss from discontinued operation)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:label="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:label="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:label="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsTable" xlink:to="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaapDisposalGroupsIncludingDiscontinuedOperationsNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:to="loc_us-gaapDisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:label="loc_us-gaapDisposalGroupsIncludingDiscontinuedOperationsNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis" xlink:to="loc_us-gaapDisposalGroupsIncludingDiscontinuedOperationsNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_CognoGroupIncMember" xlink:label="loc_NIXXCognoGroupIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapDisposalGroupsIncludingDiscontinuedOperationsNameDomain" xlink:to="loc_NIXXCognoGroupIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationRevenue" xlink:label="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationRevenue_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationRevenue_30" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold" xlink:label="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationCostsOfGoodsSold_30" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGrossProfitLoss" xlink:label="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationGrossProfitLoss_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationGrossProfitLoss_30" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationOperatingExpenseAbstract" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationOperatingExpenseAbstract_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationOperatingExpenseAbstract_30" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationSalesAndMarketing" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationSalesAndMarketing_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationSalesAndMarketing_30" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationProductDevelopment" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationProductDevelopment_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationProductDevelopment_30" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense" xlink:label="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationGeneralAndAdministrativeExpense_30" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationAmortizationOfIntangibles" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationAmortizationOfIntangibles_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationAmortizationOfIntangibles_30" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationOperatingExpense" xlink:label="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationOperatingExpense_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapDisposalGroupIncludingDiscontinuedOperationOperatingExpense_30" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_LossFromDiscontinuedOperations" xlink:label="loc_NIXXLossFromDiscontinuedOperations_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXLossFromDiscontinuedOperations_30" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationOtherIncomeExpensesAbstract" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationOtherIncomeExpensesAbstract_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationOtherIncomeExpensesAbstract_30" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationChangeInFairValueOfWarrantLliability" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationChangeInFairValueOfWarrantLliability_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationChangeInFairValueOfWarrantLliability_30" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationChangeInFairValueOfDerivativeLiability" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationChangeInFairValueOfDerivativeLiability_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationChangeInFairValueOfDerivativeLiability_30" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationOtherIncomeExpense" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationOtherIncomeExpense_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationOtherIncomeExpense_30" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromDiscontinuedOperationsNetOfTax" xlink:label="loc_us-gaapIncomeLossFromDiscontinuedOperationsNetOfTax_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapIncomeLossFromDiscontinuedOperationsNetOfTax_30" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationAndAmortizationDiscontinuedOperations" xlink:label="loc_us-gaapDepreciationAndAmortizationDiscontinuedOperations_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_us-gaapDepreciationAndAmortizationDiscontinuedOperations_30" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DisposalGroupIncludingDiscontinuedOperationEquityBasedCompensationExpenseStock" xlink:label="loc_NIXXDisposalGroupIncludingDiscontinuedOperationEquityBasedCompensationExpenseStock_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapIncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsLineItems" xlink:to="loc_NIXXDisposalGroupIncludingDiscontinuedOperationEquityBasedCompensationExpenseStock_30" xlink:type="arc" order="16" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/LoansPayableAndFinancingAgreementsDetailsNarrative" xlink:title="999043 - Disclosure - LOANS PAYABLE AND FINANCING AGREEMENTS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtLineItems" xlink:label="loc_us-gaapShortTermDebtLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShortTermDebtTable" xlink:label="loc_us-gaapScheduleOfShortTermDebtTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapScheduleOfShortTermDebtTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis" xlink:label="loc_srtCounterpartyNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShortTermDebtTable" xlink:to="loc_srtCounterpartyNameAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srtRepurchaseAgreementCounterpartyNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtCounterpartyNameAxis" xlink:to="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srtRepurchaseAgreementCounterpartyNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtCounterpartyNameAxis" xlink:to="loc_srtRepurchaseAgreementCounterpartyNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_NovoGroupMember" xlink:label="loc_NIXXNovoGroupMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXNovoGroupMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_MontageCapitalIILPMember" xlink:label="loc_NIXXMontageCapitalIILPMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXMontageCapitalIILPMember_90" xlink:type="arc" order="92" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransactionTypeAxis" xlink:label="loc_us-gaapTransactionTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShortTermDebtTable" xlink:to="loc_us-gaapTransactionTypeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransactionDomain" xlink:label="loc_us-gaapTransactionDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTransactionTypeAxis" xlink:to="loc_us-gaapTransactionDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransactionDomain" xlink:label="loc_us-gaapTransactionDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTransactionTypeAxis" xlink:to="loc_us-gaapTransactionDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SharesIssuedMember" xlink:label="loc_NIXXSharesIssuedMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXSharesIssuedMember_50" xlink:type="arc" order="52" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SharesToBeIssuedMember" xlink:label="loc_NIXXSharesToBeIssuedMember_60" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXSharesToBeIssuedMember_60" xlink:type="arc" order="62" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeAxis" xlink:label="loc_us-gaapShortTermDebtTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShortTermDebtTable" xlink:to="loc_us-gaapShortTermDebtTypeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShortTermDebtTypeDomain" xlink:label="loc_us-gaapShortTermDebtTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShortTermDebtTypeAxis" xlink:to="loc_us-gaapShortTermDebtTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_LoanAndSecurityAgreementMember" xlink:label="loc_NIXXLoanAndSecurityAgreementMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtTypeDomain" xlink:to="loc_NIXXLoanAndSecurityAgreementMember_90" xlink:type="arc" order="91" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShortTermDebtTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ConvertibleLineOfCreditAgreementMember" xlink:label="loc_NIXXConvertibleLineOfCreditAgreementMember_110" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_NIXXConvertibleLineOfCreditAgreementMember_110" xlink:type="arc" order="111" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_PremiumFinancingAgreementMember" xlink:label="loc_NIXXPremiumFinancingAgreementMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_NIXXPremiumFinancingAgreementMember_150" xlink:type="arc" order="151" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LongTermNotesAndLoans" xlink:label="loc_us-gaapLongTermNotesAndLoans_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapLongTermNotesAndLoans_190" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt" xlink:label="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapGainsLossesOnExtinguishmentOfDebt_190" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentMaturityDate" xlink:label="loc_us-gaapDebtInstrumentMaturityDate_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapDebtInstrumentMaturityDate_190" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1" xlink:label="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapDebtInstrumentConvertibleConversionPrice1_190" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentAmount1_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentAmount1_190" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DebtConversionConvertedInterestAmount1" xlink:label="loc_NIXXDebtConversionConvertedInterestAmount1_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_NIXXDebtConversionConvertedInterestAmount1_190" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockSharesIssued1" xlink:label="loc_us-gaapConversionOfStockSharesIssued1_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapConversionOfStockSharesIssued1_190" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentFaceAmount" xlink:label="loc_us-gaapDebtInstrumentFaceAmount_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapDebtInstrumentFaceAmount_190" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ForgivenAmountFirstCallReceived" xlink:label="loc_NIXXForgivenAmountFirstCallReceived_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_NIXXForgivenAmountFirstCallReceived_190" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ForgivenAmountSecondCallReceived" xlink:label="loc_NIXXForgivenAmountSecondCallReceived_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_NIXXForgivenAmountSecondCallReceived_190" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LegalFees" xlink:label="loc_us-gaapLegalFees_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapLegalFees_190" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_LoanAgreementAmountDue" xlink:label="loc_NIXXLoanAgreementAmountDue_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_NIXXLoanAgreementAmountDue_190" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_IssueOfWarrantsToPurchase" xlink:label="loc_NIXXIssueOfWarrantsToPurchase_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_NIXXIssueOfWarrantsToPurchase_190" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsIssued" xlink:label="loc_NIXXWarrantsIssued_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_NIXXWarrantsIssued_190" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantExercisable" xlink:label="loc_NIXXWarrantExercisable_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_NIXXWarrantExercisable_190" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1" xlink:label="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1_190" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PaymentsForRepurchaseOfWarrants" xlink:label="loc_us-gaapPaymentsForRepurchaseOfWarrants_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapPaymentsForRepurchaseOfWarrants_190" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityPeriodicPaymentPrincipal" xlink:label="loc_us-gaapLineOfCreditFacilityPeriodicPaymentPrincipal_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapLineOfCreditFacilityPeriodicPaymentPrincipal_190" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromLinesOfCredit" xlink:label="loc_us-gaapProceedsFromLinesOfCredit_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapProceedsFromLinesOfCredit_190" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity" xlink:label="loc_us-gaapLineOfCreditFacilityMaximumBorrowingCapacity_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapLineOfCreditFacilityMaximumBorrowingCapacity_190" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityInterestRateDuringPeriod" xlink:label="loc_us-gaapLineOfCreditFacilityInterestRateDuringPeriod_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapLineOfCreditFacilityInterestRateDuringPeriod_190" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaapCommonStockParOrStatedValuePerShare_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapCommonStockParOrStatedValuePerShare_190" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaapSharePrice_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapSharePrice_190" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCredit" xlink:label="loc_us-gaapLineOfCredit_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapLineOfCredit_190" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod" xlink:label="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapDebtInstrumentInterestRateDuringPeriod_190" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LoansPayable" xlink:label="loc_us-gaapLoansPayable_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShortTermDebtLineItems" xlink:to="loc_us-gaapLoansPayable_190" xlink:type="arc" order="25" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/StockholdersEquityDetailsNarrative" xlink:title="999044 - Disclosure - STOCKHOLDERS&#8217; EQUITY (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockLineItems" xlink:label="loc_us-gaapClassOfStockLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfStockByClassTable" xlink:label="loc_us-gaapScheduleOfStockByClassTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapScheduleOfStockByClassTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementClassOfStockAxis" xlink:label="loc_us-gaapStatementClassOfStockAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapStatementClassOfStockAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfStockDomain" xlink:label="loc_us-gaapClassOfStockDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapStatementClassOfStockAxis" xlink:to="loc_us-gaapClassOfStockDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesDPreferredStockMember" xlink:label="loc_us-gaapSeriesDPreferredStockMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesDPreferredStockMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesEPreferredStockMember" xlink:label="loc_us-gaapSeriesEPreferredStockMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesEPreferredStockMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SeriesFPreferredStockMember" xlink:label="loc_us-gaapSeriesFPreferredStockMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapSeriesFPreferredStockMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_PreferredStockPenaltiesMember" xlink:label="loc_NIXXPreferredStockPenaltiesMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_NIXXPreferredStockPenaltiesMember_100" xlink:type="arc" order="101" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember" xlink:label="loc_us-gaapCommonStockMember_330" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_us-gaapCommonStockMember_330" xlink:type="arc" order="333" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_RestrictedStockUnitsMember" xlink:label="loc_NIXXRestrictedStockUnitsMember_340" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockDomain" xlink:to="loc_NIXXRestrictedStockUnitsMember_340" xlink:type="arc" order="343" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransactionTypeAxis" xlink:label="loc_us-gaapTransactionTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapTransactionTypeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransactionDomain" xlink:label="loc_us-gaapTransactionDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTransactionTypeAxis" xlink:to="loc_us-gaapTransactionDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TransactionDomain" xlink:label="loc_us-gaapTransactionDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTransactionTypeAxis" xlink:to="loc_us-gaapTransactionDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SecuritiesPurchaseAgreementsMember" xlink:label="loc_NIXXSecuritiesPurchaseAgreementsMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXSecuritiesPurchaseAgreementsMember_150" xlink:type="arc" order="151" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SharesIssuedMember" xlink:label="loc_NIXXSharesIssuedMember_180" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXSharesIssuedMember_180" xlink:type="arc" order="182" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SharesToBeIssuedMember" xlink:label="loc_NIXXSharesToBeIssuedMember_190" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXSharesToBeIssuedMember_190" xlink:type="arc" order="192" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_AssetPurchaseAgreementMember" xlink:label="loc_NIXXAssetPurchaseAgreementMember_320" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXAssetPurchaseAgreementMember_320" xlink:type="arc" order="321" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ManagementConsultingAgreementMember" xlink:label="loc_NIXXManagementConsultingAgreementMember_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXManagementConsultingAgreementMember_420" xlink:type="arc" order="421" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_PreviousTransactionMember" xlink:label="loc_NIXXPreviousTransactionMember_430" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXPreviousTransactionMember_430" xlink:type="arc" order="431" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_FormerConsultantMember" xlink:label="loc_NIXXFormerConsultantMember_460" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapTransactionDomain" xlink:to="loc_NIXXFormerConsultantMember_460" xlink:type="arc" order="461" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestorMember" xlink:label="loc_us-gaapInvestorMember_150" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_us-gaapInvestorMember_150" xlink:type="arc" order="152" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_CounterpartyNameAxis" xlink:label="loc_srtCounterpartyNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_srtCounterpartyNameAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srtRepurchaseAgreementCounterpartyNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtCounterpartyNameAxis" xlink:to="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RepurchaseAgreementCounterpartyNameDomain" xlink:label="loc_srtRepurchaseAgreementCounterpartyNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtCounterpartyNameAxis" xlink:to="loc_srtRepurchaseAgreementCounterpartyNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_NovoGroupMember" xlink:label="loc_NIXXNovoGroupMember_170" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXNovoGroupMember_170" xlink:type="arc" order="171" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_NonExecutiveBoardMembersMember" xlink:label="loc_NIXXNonExecutiveBoardMembersMember_330" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXNonExecutiveBoardMembersMember_330" xlink:type="arc" order="332" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ChairmanOfTheBoardMember" xlink:label="loc_NIXXChairmanOfTheBoardMember_360" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXChairmanOfTheBoardMember_360" xlink:type="arc" order="362" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EmployeesAndAgentsOfTheCompanyMember" xlink:label="loc_NIXXEmployeesAndAgentsOfTheCompanyMember_390" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXEmployeesAndAgentsOfTheCompanyMember_390" xlink:type="arc" order="392" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_QuantumPROUMember" xlink:label="loc_NIXXQuantumPROUMember_420" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXQuantumPROUMember_420" xlink:type="arc" order="422" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_ConsultantMember" xlink:label="loc_NIXXConsultantMember_430" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXConsultantMember_430" xlink:type="arc" order="432" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SavitrConsultantMember" xlink:label="loc_NIXXSavitrConsultantMember_440" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRepurchaseAgreementCounterpartyNameDomain" xlink:to="loc_NIXXSavitrConsultantMember_440" xlink:type="arc" order="441" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_TechnologyLicenseAndCommercializationAgreementMember" xlink:label="loc_NIXXTechnologyLicenseAndCommercializationAgreementMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_NIXXTechnologyLicenseAndCommercializationAgreementMember_200" xlink:type="arc" order="201" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis" xlink:label="loc_us-gaapAssetAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapAssetAcquisitionAxis" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain" xlink:label="loc_us-gaapAssetAcquisitionDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAssetAcquisitionAxis" xlink:to="loc_us-gaapAssetAcquisitionDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain" xlink:label="loc_us-gaapAssetAcquisitionDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAssetAcquisitionAxis" xlink:to="loc_us-gaapAssetAcquisitionDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_GOLQMember" xlink:label="loc_NIXXGOLQMember_200" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXGOLQMember_200" xlink:type="arc" order="202" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SavitrTechOUMember" xlink:label="loc_NIXXSavitrTechOUMember_210" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXSavitrTechOUMember_210" xlink:type="arc" order="211" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_AquaSoftwareTechnologiesMember" xlink:label="loc_NIXXAquaSoftwareTechnologiesMember_230" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXAquaSoftwareTechnologiesMember_230" xlink:type="arc" order="231" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_NexGenAIHoldingGroupIncMember" xlink:label="loc_NIXXNexGenAIHoldingGroupIncMember_240" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXNexGenAIHoldingGroupIncMember_240" xlink:type="arc" order="241" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_NexGenAIAPAMember" xlink:label="loc_NIXXNexGenAIAPAMember_250" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXNexGenAIAPAMember_250" xlink:type="arc" order="251" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis" xlink:label="loc_us-gaapBusinessAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapBusinessAcquisitionAxis" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain" xlink:label="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapBusinessAcquisitionAxis" xlink:to="loc_us-gaapBusinessAcquisitionAcquireeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EverythinkAssetAcquisitionMember" xlink:label="loc_NIXXEverythinkAssetAcquisitionMember_310" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapBusinessAcquisitionAcquireeDomain" xlink:to="loc_NIXXEverythinkAssetAcquisitionMember_310" xlink:type="arc" order="311" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaapPlanNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapPlanNameAxis" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EquityIncentivePlan2021Member" xlink:label="loc_NIXXEquityIncentivePlan2021Member_330" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_NIXXEquityIncentivePlan2021Member_330" xlink:type="arc" order="331" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EquityIncentivePlan2024Member" xlink:label="loc_NIXXEquityIncentivePlan2024Member_390" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_NIXXEquityIncentivePlan2024Member_390" xlink:type="arc" order="391" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_Plan2024Member" xlink:label="loc_NIXXPlan2024Member_470" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_NIXXPlan2024Member_470" xlink:type="arc" order="471" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualAxis" xlink:label="loc_srtTitleOfIndividualAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_srtTitleOfIndividualAxis" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain" xlink:label="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtTitleOfIndividualAxis" xlink:to="loc_srtTitleOfIndividualWithRelationshipToEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ChiefExecutiveOfficerMember" xlink:label="loc_srtChiefExecutiveOfficerMember_470" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtTitleOfIndividualWithRelationshipToEntityDomain" xlink:to="loc_srtChiefExecutiveOfficerMember_470" xlink:type="arc" order="472" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfStockByClassTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedStockUnitsRSUMember" xlink:label="loc_us-gaapRestrictedStockUnitsRSUMember_470" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaapRestrictedStockUnitsRSUMember_470" xlink:type="arc" order="473" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesAuthorized" xlink:label="loc_us-gaapPreferredStockSharesAuthorized_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockSharesAuthorized_530" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockParOrStatedValuePerShare" xlink:label="loc_us-gaapPreferredStockParOrStatedValuePerShare_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockParOrStatedValuePerShare_530" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesIssued" xlink:label="loc_us-gaapPreferredStockSharesIssued_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockSharesIssued_530" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PreferredStockSharesOutstanding" xlink:label="loc_us-gaapPreferredStockSharesOutstanding_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapPreferredStockSharesOutstanding_530" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesAuthorized" xlink:label="loc_us-gaapCommonStockSharesAuthorized_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCommonStockSharesAuthorized_530" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesNewIssues_530" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueNewIssues" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueNewIssues_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueNewIssues_530" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_AccruedPenaltyAmount" xlink:label="loc_NIXXAccruedPenaltyAmount_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_NIXXAccruedPenaltyAmount_530" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_StockIssuedDuringPeriodValueConversionOfLiabilities" xlink:label="loc_NIXXStockIssuedDuringPeriodValueConversionOfLiabilities_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_NIXXStockIssuedDuringPeriodValueConversionOfLiabilities_530" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharesIssued" xlink:label="loc_us-gaapSharesIssued_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharesIssued_530" xlink:type="arc" order="9" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccruedLiabilitiesCurrent" xlink:label="loc_us-gaapAccruedLiabilitiesCurrent_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapAccruedLiabilitiesCurrent_530" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockParOrStatedValuePerShare" xlink:label="loc_us-gaapCommonStockParOrStatedValuePerShare_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCommonStockParOrStatedValuePerShare_530" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding" xlink:label="loc_us-gaapCommonStockSharesOutstanding_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCommonStockSharesOutstanding_530" xlink:type="arc" order="12" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromIssuanceOfCommonStock" xlink:label="loc_us-gaapProceedsFromIssuanceOfCommonStock_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapProceedsFromIssuanceOfCommonStock_530" xlink:type="arc" order="13" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtConversionConvertedInstrumentAmount1" xlink:label="loc_us-gaapDebtConversionConvertedInstrumentAmount1_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapDebtConversionConvertedInstrumentAmount1_530" xlink:type="arc" order="14" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_DebtConversionConvertedInterestAmount1" xlink:label="loc_NIXXDebtConversionConvertedInterestAmount1_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_NIXXDebtConversionConvertedInterestAmount1_530" xlink:type="arc" order="15" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConversionOfStockSharesIssued1" xlink:label="loc_us-gaapConversionOfStockSharesIssued1_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapConversionOfStockSharesIssued1_530" xlink:type="arc" order="16" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesPurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_530" xlink:type="arc" order="17" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValuePurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_530" xlink:type="arc" order="18" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionPriceOfAcquisitionExpected" xlink:label="loc_us-gaapAssetAcquisitionPriceOfAcquisitionExpected_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapAssetAcquisitionPriceOfAcquisitionExpected_530" xlink:type="arc" order="19" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CededPremiumsPayable" xlink:label="loc_us-gaapCededPremiumsPayable_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapCededPremiumsPayable_530" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesAcquisitions_530" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharePrice" xlink:label="loc_us-gaapSharePrice_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharePrice_530" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessCombinationPriceOfAcquisitionExpected" xlink:label="loc_us-gaapBusinessCombinationPriceOfAcquisitionExpected_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapBusinessCombinationPriceOfAcquisitionExpected_530" xlink:type="arc" order="23" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_StockGrantedDuringPeriodSharesSharebasedCompensation" xlink:label="loc_NIXXStockGrantedDuringPeriodSharesSharebasedCompensation_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_NIXXStockGrantedDuringPeriodSharesSharebasedCompensation_530" xlink:type="arc" order="24" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_530" xlink:type="arc" order="25" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockGrantedDuringPeriodValueSharebasedCompensation" xlink:label="loc_us-gaapStockGrantedDuringPeriodValueSharebasedCompensation_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockGrantedDuringPeriodValueSharebasedCompensation_530" xlink:type="arc" order="26" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_530" xlink:type="arc" order="27" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_VestedSharesRemainingIssued" xlink:label="loc_NIXXVestedSharesRemainingIssued_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_NIXXVestedSharesRemainingIssued_530" xlink:type="arc" order="28" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesShareBasedCompensation_530" xlink:type="arc" order="29" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueShareBasedCompensation_530" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesIssuedForServices_530" xlink:type="arc" order="31" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueIssuedForServices" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueIssuedForServices_530" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesOther_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesOther_530" xlink:type="arc" order="33" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueOther" xlink:label="loc_us-gaapStockIssuedDuringPeriodValueOther_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValueOther_530" xlink:type="arc" order="34" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod_530" xlink:type="arc" order="35" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_530" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfStockLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_530" xlink:type="arc" order="36" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/StockOptionsAndWarrantsDetailsNarrative" xlink:title="999045 - Disclosure - STOCK OPTIONS AND WARRANTS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:label="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameAxis" xlink:label="loc_us-gaapPlanNameAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapPlanNameAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PlanNameDomain" xlink:label="loc_us-gaapPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapPlanNameAxis" xlink:to="loc_us-gaapPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EquityIncentivePlan2021Member" xlink:label="loc_NIXXEquityIncentivePlan2021Member_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_NIXXEquityIncentivePlan2021Member_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_EquityIncentivePlan2024Member" xlink:label="loc_NIXXEquityIncentivePlan2024Member_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapPlanNameDomain" xlink:to="loc_NIXXEquityIncentivePlan2024Member_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeAxis" xlink:label="loc_srtRangeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_srtRangeAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_RangeMember" xlink:label="loc_srtRangeMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtRangeAxis" xlink:to="loc_srtRangeMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MinimumMember" xlink:label="loc_srtMinimumMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMinimumMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MaximumMember" xlink:label="loc_srtMaximumMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtRangeMember" xlink:to="loc_srtMaximumMember_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AwardTypeAxis" xlink:label="loc_us-gaapAwardTypeAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapAwardTypeAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAwardTypeAxis" xlink:to="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockOptionMember" xlink:label="loc_us-gaapStockOptionMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaapStockOptionMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsMember" xlink:label="loc_NIXXWarrantsMember_100" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_NIXXWarrantsMember_100" xlink:type="arc" order="101" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightAxis" xlink:label="loc_us-gaapClassOfWarrantOrRightAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable" xlink:to="loc_us-gaapClassOfWarrantOrRightAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ClassOfWarrantOrRightDomain" xlink:label="loc_us-gaapClassOfWarrantOrRightDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapClassOfWarrantOrRightAxis" xlink:to="loc_us-gaapClassOfWarrantOrRightDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsCognoGroupMember" xlink:label="loc_NIXXWarrantsCognoGroupMember_90" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapClassOfWarrantOrRightDomain" xlink:to="loc_NIXXWarrantsCognoGroupMember_90" xlink:type="arc" order="91" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssued1" xlink:label="loc_us-gaapStockIssued1_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapStockIssued1_130" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_130" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_130" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AllocatedShareBasedCompensationExpense" xlink:label="loc_us-gaapAllocatedShareBasedCompensationExpense_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapAllocatedShareBasedCompensationExpense_130" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions" xlink:label="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapEmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_130" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromStockOptionsExercised" xlink:label="loc_us-gaapProceedsFromStockOptionsExercised_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapProceedsFromStockOptionsExercised_130" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_SharesWarrantsTransferred" xlink:label="loc_NIXXSharesWarrantsTransferred_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_NIXXSharesWarrantsTransferred_130" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProceedsFromWarrantExercises" xlink:label="loc_us-gaapProceedsFromWarrantExercises_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapProceedsFromWarrantExercises_130" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice" xlink:label="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_130" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1" xlink:label="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_130" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems" xlink:to="loc_us-gaapSharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_130" xlink:type="arc" order="9" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/CommitmentsAndContingenciesDetailsNarrative" xlink:title="999046 - Disclosure - COMMITMENTS AND CONTINGENCIES (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesLineItems" xlink:label="loc_us-gaapLossContingenciesLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LossContingenciesTable" xlink:label="loc_us-gaapLossContingenciesTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapLossContingenciesLineItems" xlink:to="loc_us-gaapLossContingenciesTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseAxis" xlink:label="loc_srtLitigationCaseAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapLossContingenciesTable" xlink:to="loc_srtLitigationCaseAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srtLitigationCaseTypeDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srtLitigationCaseAxis" xlink:to="loc_srtLitigationCaseTypeDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_LitigationCaseTypeDomain" xlink:label="loc_srtLitigationCaseTypeDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_srtLitigationCaseAxis" xlink:to="loc_srtLitigationCaseTypeDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_PiplIncMember" xlink:label="loc_NIXXPiplIncMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtLitigationCaseTypeDomain" xlink:to="loc_NIXXPiplIncMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_CreditorsAdjustmentBureauMember" xlink:label="loc_NIXXCreditorsAdjustmentBureauMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtLitigationCaseTypeDomain" xlink:to="loc_NIXXCreditorsAdjustmentBureauMember_10" xlink:type="arc" order="11" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_HireTeammateMember" xlink:label="loc_NIXXHireTeammateMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srtLitigationCaseTypeDomain" xlink:to="loc_NIXXHireTeammateMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LitigationReserveCurrent" xlink:label="loc_us-gaapLitigationReserveCurrent_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapLossContingenciesLineItems" xlink:to="loc_us-gaapLitigationReserveCurrent_40" xlink:type="arc" order="0" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/RelatedPartyTransactionsDetailsNarrative" xlink:title="999047 - Disclosure - RELATED PARTY TRANSACTIONS (Details Narrative)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionLineItems" xlink:label="loc_us-gaapRelatedPartyTransactionLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:label="loc_us-gaapScheduleOfRelatedPartyTransactionsByRelatedPartyTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis" xlink:label="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RelatedPartyDomain" xlink:label="loc_us-gaapRelatedPartyDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapRelatedPartyTransactionsByRelatedPartyAxis" xlink:to="loc_us-gaapRelatedPartyDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_RecruiterComMauritiusMember" xlink:label="loc_NIXXRecruiterComMauritiusMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_NIXXRecruiterComMauritiusMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_LogiqIncMember" xlink:label="loc_NIXXLogiqIncMember_50" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyDomain" xlink:to="loc_NIXXLogiqIncMember_50" xlink:type="arc" order="51" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TypeOfArrangementAxis" xlink:label="loc_us-gaapTypeOfArrangementAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="loc_us-gaapTypeOfArrangementAxis" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember" xlink:label="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapTypeOfArrangementAxis" xlink:to="loc_us-gaapArrangementsAndNonarrangementTransactionsMember_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_TechnologyLicenseAndCommercializationAgreementMember" xlink:label="loc_NIXXTechnologyLicenseAndCommercializationAgreementMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapArrangementsAndNonarrangementTransactionsMember" xlink:to="loc_NIXXTechnologyLicenseAndCommercializationAgreementMember_20" xlink:type="arc" order="21" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionAxis" xlink:label="loc_us-gaapAssetAcquisitionAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="loc_us-gaapAssetAcquisitionAxis" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain" xlink:label="loc_us-gaapAssetAcquisitionDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapAssetAcquisitionAxis" xlink:to="loc_us-gaapAssetAcquisitionDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AssetAcquisitionDomain" xlink:label="loc_us-gaapAssetAcquisitionDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapAssetAcquisitionAxis" xlink:to="loc_us-gaapAssetAcquisitionDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_GOLQMember" xlink:label="loc_NIXXGOLQMember_20" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapAssetAcquisitionDomain" xlink:to="loc_NIXXGOLQMember_20" xlink:type="arc" order="22" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_LegalEntityAxis" xlink:label="loc_deiLegalEntityAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="loc_deiLegalEntityAxis" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.sec.gov/dei/2026/dei-2026.xsd#dei_EntityDomain" xlink:label="loc_deiEntityDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_deiLegalEntityAxis" xlink:to="loc_deiEntityDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantTozpurchaseMember" xlink:label="loc_NIXXWarrantTozpurchaseMember_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_deiEntityDomain" xlink:to="loc_NIXXWarrantTozpurchaseMember_30" xlink:type="arc" order="32" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfRelatedPartyTransactionsByRelatedPartyTable" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsByMajorClassAxis" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_GoLogiqAssetsMember" xlink:label="loc_NIXXGoLogiqAssetsMember_40" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapFiniteLivedIntangibleAssetsMajorClassNameDomain" xlink:to="loc_NIXXGoLogiqAssetsMember_40" xlink:type="arc" order="41" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaapResearchAndDevelopmentExpense_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapResearchAndDevelopmentExpense_80" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesPurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodSharesPurchaseOfAssets_80" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValuePurchaseOfAssets" xlink:label="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapStockIssuedDuringPeriodValuePurchaseOfAssets_80" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsIssuedShares" xlink:label="loc_NIXXWarrantsIssuedShares_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_NIXXWarrantsIssuedShares_80" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsIssuedValue1" xlink:label="loc_NIXXWarrantsIssuedValue1_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_NIXXWarrantsIssuedValue1_80" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsGross" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsGross_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsGross_80" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsAccumulatedAmortization_80" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FiniteLivedIntangibleAssetsNet" xlink:label="loc_us-gaapFiniteLivedIntangibleAssetsNet_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapFiniteLivedIntangibleAssetsNet_80" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaapSellingAndMarketingExpense_80" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapRelatedPartyTransactionLineItems" xlink:to="loc_us-gaapSellingAndMarketingExpense_80" xlink:type="arc" order="8" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/SegmentReportingDetails-SegmentInformation" xlink:title="999048 - Disclosure - SEGMENT REPORTING (Details - Segment information)">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems" xlink:label="loc_us-gaapSegmentReportingInformationLineItems" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable" xlink:label="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:type="arc" order="10" xbrldt:closed="true" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsAxis" xlink:label="loc_us-gaapSubsegmentsAxis" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaapScheduleOfSegmentReportingInformationBySegmentTable" xlink:to="loc_us-gaapSubsegmentsAxis" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsDomain" xlink:label="loc_us-gaapSubsegmentsDomain" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaapSubsegmentsAxis" xlink:to="loc_us-gaapSubsegmentsDomain" xlink:type="arc" order="20" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SubsegmentsDomain" xlink:label="loc_us-gaapSubsegmentsDomain_10" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xbrldt:contextElement="segment" xlink:from="loc_us-gaapSubsegmentsAxis" xlink:to="loc_us-gaapSubsegmentsDomain_10" xlink:type="arc" order="30" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_TelecommMember" xlink:label="loc_NIXXTelecommMember_0" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSubsegmentsDomain" xlink:to="loc_NIXXTelecommMember_0" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesAbstract" xlink:label="loc_us-gaapRevenuesAbstract_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapRevenuesAbstract_30" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Revenues" xlink:label="loc_us-gaapRevenues_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapRevenues_30" xlink:type="arc" order="1" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpensesAbstract" xlink:label="loc_us-gaapOperatingExpensesAbstract_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapOperatingExpensesAbstract_30" xlink:type="arc" order="2" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherCostAndExpenseOperating" xlink:label="loc_us-gaapOtherCostAndExpenseOperating_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapOtherCostAndExpenseOperating_30" xlink:type="arc" order="3" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingAndMarketingExpense" xlink:label="loc_us-gaapSellingAndMarketingExpense_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapSellingAndMarketingExpense_30" xlink:type="arc" order="4" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ResearchAndDevelopmentExpense" xlink:label="loc_us-gaapResearchAndDevelopmentExpense_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapResearchAndDevelopmentExpense_30" xlink:type="arc" order="5" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets" xlink:label="loc_us-gaapAmortizationOfIntangibleAssets_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapAmortizationOfIntangibleAssets_30" xlink:type="arc" order="6" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GeneralAndAdministrativeExpense" xlink:label="loc_us-gaapGeneralAndAdministrativeExpense_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapGeneralAndAdministrativeExpense_30" xlink:type="arc" order="7" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingExpenses" xlink:label="loc_us-gaapOperatingExpenses_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapOperatingExpenses_30" xlink:type="arc" order="8" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss" xlink:label="loc_us-gaapOperatingIncomeLoss_30" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapSegmentReportingInformationLineItems" xlink:to="loc_us-gaapOperatingIncomeLoss_30" xlink:type="arc" order="9" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://trulitechnologies.com/role/SegmentReportingDetailsNarrative" xlink:title="999049 - Disclosure - SEGMENT REPORTING (Details Narrative)" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/PvpExecutiveCategoriesOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/PvpAdjustmentsOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/IndividualsOnly" />
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/AwardTypeOnly">
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:label="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_OptionsMember" xlink:label="loc_NIXXOptionsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_NIXXOptionsMember" xlink:type="arc" order="0" />
      <link:loc xlink:type="locator" xlink:href="nixx-20260331.xsd#NIXX_WarrantsMember" xlink:label="loc_NIXXWarrantsMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_NIXXWarrantsMember" xlink:type="arc" order="10" />
      <link:loc xlink:type="locator" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockOptionMember" xlink:label="loc_us-gaapStockOptionMember" />
      <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaapShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain" xlink:to="loc_us-gaapStockOptionMember" xlink:type="arc" order="20" />
    </link:definitionLink>
    <link:definitionLink xlink:type="extended" xlink:role="http://xbrl.sec.gov/ecd/role/TradingArrangementsOnly" />
</link:linkbase>
