There are 391 fifteen-letter words containing A, I, N and V, https://www.bestwordlist.com/c/a/4/15letterwordswithainv.htm
ACQUISITIVENESS ADDICTIVENESSES ADVERSARINESSES ADVISABLENESSES
AFFECTIVENESSES ALTERNATIVENESS ANTICOMPETITIVE ANTICONVULSANTS
ANTICONVULSIVES ANTIDERIVATIVES ANTIDEVELOPMENT ANTIPROGRESSIVE
ANTIRETROVIRALS ANTISPECULATIVE ANTIVIVISECTION ARGUMENTATIVELY
ARIBOFLAVINOSES ARIBOFLAVINOSIS ASSENTIVENESSES ASSERTIVENESSES
ASTRONAVIGATION ASTRONAVIGATORS ATTENTIVENESSES ATTRIBUTIVENESS
AVAILABLENESSES BIOEQUIVALENCES BOUGAINVILLAEAS CARNIVOROUSNESS
CAUSATIVENESSES CIRCUMNAVIGABLE CIRCUMNAVIGATED CIRCUMNAVIGATES
CIRCUMNAVIGATOR CIRCUMVALLATING CIRCUMVALLATION CIVILIANISATION
CIVILIANIZATION COINVESTIGATORS COMBATIVENESSES COMMUNICATIVELY
COMPARATIVENESS CONCEIVABLENESS CONCENTRATIVELY CONSERVATIONIST
CONSERVATORIUMS CONSERVATORSHIP CONSIDERATIVELY CONTEMPLATIVELY
CONTRACTIVENESS CONTRADICTIVELY CONTRAPOSITIVES CONTRAVALLATION
CONTROVERSIALLY CONVALESCENCIES CONVENTIONALISE CONVENTIONALISM
CONVENTIONALIST CONVENTIONALITY CONVENTIONALIZE CONVERSATIONISM
CONVERSATIONIST CONVEYORISATION CONVEYORIZATION CONVOCATIONISTS
CONVULSIONARIES COOPERATIVENESS CORRELATIVENESS COSIGNIFICATIVE
COUNTERACTIVELY COUNTERADAPTIVE COUNTERINVASION COUNTERVAILABLE
DECONTAMINATIVE DEINDIVIDUATION DEMONSTRATIVELY DERIVATISATIONS
DERIVATIZATIONS DESILVERISATION DESILVERIZATION DETERMINATIVELY
DEVALORISATIONS DEVALORIZATIONS DEVITALISATIONS DEVITALIZATIONS
DEVITRIFICATION DEVOTIONALITIES DIFFRACTIVENESS DISADVANTAGEOUS
DISINVIGORATING DISPUTATIVENESS DISSOLVABLENESS DIVERSIFICATION
DORSIVENTRALITY DORSOVENTRALITY ELECTRONEGATIVE ENVENOMISATIONS
ENVENOMIZATIONS ENVIRONMENTALLY EQUIVOCALNESSES EVANGELICALISMS
EVANGELICALNESS EVANGELISATIONS EVANGELISTARIES EVANGELISTARION
EVANGELIZATIONS EVERLASTINGNESS EVOCATIVENESSES EXCOMMUNICATIVE
EXPANSIVENESSES EXPERIMENTATIVE EXTENSIVISATION EXTENSIVIZATION
FLAVOURDYNAMICS FORMATIVENESSES GALVANOMETRICAL GALVANOPLASTIES
GALVANOTROPISMS GOVERNABILITIES GOVERNMENTALISE GOVERNMENTALISM
GOVERNMENTALIST GOVERNMENTALIZE GRAVIPERCEPTION GRAVITATIONALLY
HETERONORMATIVE HYPERSALIVATION HYPERVENTILATED HYPERVENTILATES
HYPERVIGILANCES HYPOVENTILATION IMAGINATIVENESS IMITATIVENESSES
IMMOVABLENESSES IMPASSIVENESSES IMPERVIABLENESS IMPLICATIVENESS
IMPROVISATIONAL INADVISABLENESS INATTENTIVENESS INCENTIVISATION
INCENTIVIZATION INCOMMUNICATIVE INDIVIDUALISERS INDIVIDUALISING
INDIVIDUALISTIC INDIVIDUALITIES INDIVIDUALIZERS INDIVIDUALIZING
INEVITABILITIES INFORMATIVENESS INOPERATIVENESS INSIGNIFICATIVE
INSOLVABILITIES INTERACTIVITIES INTERBEHAVIORAL INTERBEHAVIOURS
INTERCLAVICULAR INTERDIVISIONAL INTERINDIVIDUAL INTERPROVINCIAL
INTERROGATIVELY INTERVALOMETERS INTERVISITATION INTERWEAVEMENTS
INTRAVASCULARLY INVARIABILITIES INVESTIGATIONAL INVIOLABILITIES
INVIOLATENESSES INVOLUNTARINESS INVULNERABILITY IRREMOVABLENESS
IRREVOCABLENESS ITERATIVENESSES LACTOVEGETARIAN LUCRATIVENESSES
MACROEVOLUTIONS MANEUVERABILITY MANOEUVRABILITY MISAPPREHENSIVE
MISGOVERNAUNCES MISVOCALISATION MISVOCALIZATION MULTIDIVISIONAL
MULTIWAVELENGTH NAVIGABLENESSES NEOCONSERVATISM NEOCONSERVATIVE
NONACHIEVEMENTS NONADDITIVITIES NONAVAILABILITY NONCONSERVATION
NONCONSERVATIVE NONCONVENTIONAL NONCOOPERATIVES NONCREATIVITIES
NONCULTIVATIONS NONEQUIVALENCES NONEXPLOITATIVE NONPSYCHOACTIVE
NONQUANTITATIVE NONRELATIVISTIC NORMATIVENESSES NOVOCENTENARIES
OBSERVATIONALLY OPERATIVENESSES OVERABSTRACTION OVERACHIEVEMENT
OVERADVERTISING OVERADVERTIZING OVERAPPLICATION OVERBEARINGNESS
OVERCENTRALISED OVERCENTRALISES OVERCENTRALIZED OVERCENTRALIZES
OVERCLASSIFYING OVERCOMMUNICATE OVERCOMPLIANCES OVERCULTIVATION
OVERDECORATIONS OVERDRAMATISING OVERDRAMATIZING OVERELABORATING
OVERELABORATION OVEREMOTIONALLY OVEREMPHASISING OVEREMPHASIZING
OVERENCOURAGING OVERENTERTAINED OVERENTHUSIASMS OVERESTIMATIONS
OVEREVALUATIONS OVEREXPECTATION OVEREXTRACTIONS OVERGENERALISED
OVERGENERALISES OVERGENERALIZED OVERGENERALIZES OVERGLAMORISING
OVERGLAMORIZING OVERHASTINESSES OVERIMAGINATIVE OVERMEDICATIONS
OVEROPINIONATED OVERORNAMENTING OVERPERSUASIONS OVERPOPULATIONS
OVERPREPARATION OVERPROGRAMMING OVERREGULATIONS OVERSATURATIONS
OVERSPECULATING OVERSPECULATION OVERSTIMULATING OVERSTIMULATION
OVERUTILISATION OVERUTILIZATION PENETRATIVENESS PERVASIVENESSES
PHOTOENGRAVINGS PLAINTIVENESSES POSTDEVALUATION POSTVACCINATION
PRESERVATIONIST PROCRASTINATIVE PROCREATIVENESS PROGNOSTICATIVE
PROVERBIALISING PROVERBIALIZING PROVINCIALISING PROVINCIALITIES
PROVINCIALIZING PROVOCATIVENESS QUADRIVALENCIES QUINQUEVALENCES
QUINQUIVALENCES RADIOACTIVATING RADIOACTIVATION READVERTISEMENT
READVERTIZEMENT REINVESTIGATING REINVESTIGATION REINVIGORATIONS
RELATIVISATIONS RELATIVIZATIONS REMONSTRATIVELY REPRESENTATIVES
REPRIVATISATION REPRIVATIZATION RESERVATIONISTS RETRIEVABLENESS
RETROACTIVENESS REVALORISATIONS REVALORIZATIONS REVEALINGNESSES
REVICTIMIZATION REVISUALISATION REVISUALIZATION REVITALISATIONS
REVITALIZATIONS REVIVIFICATIONS REVOLUTIONARIES REVOLUTIONARILY
SERVICEABLENESS SERVOMECHANICAL SERVOMECHANISMS SIGNIFICATIVELY
SPECULATIVENESS SUBCIVILISATION SUBCIVILIZATION SUBSTANTIVENESS
SUBSTANTIVISING SUBSTANTIVITIES SUBSTANTIVIZING SUBVERSIONARIES
SUBVOCALISATION SUBVOCALIZATION SUPERELEVATIONS SUPERINDIVIDUAL
SUPERLATIVENESS SUPEROVULATIONS TALKATIVENESSES TENOVAGINITISES
TENTATIVENESSES TERGIVERSATIONS TRANSCRIPTIVELY TRANSGRESSIVELY
TRANSVALUATIONS TRANSVESTITISMS TRIVIALISATIONS TRIVIALIZATIONS
ULTRACONVENIENT UNADVISABLENESS UNADVISEDNESSES UNAUTHORITATIVE
UNAVAILABLENESS UNAVOIDABLENESS UNBELIEVABILITY UNCOMBATIVENESS
UNCOMMUNICATIVE UNCONTROVERSIAL UNCONVENTIONALS UNCOOPERATIVELY
UNDEMONSTRATIVE UNDERACTIVITIES UNDERVALUATIONS UNEQUIVOCALNESS
UNIMAGINATIVELY UNINFORMATIVELY UNIVERSALISABLE UNIVERSALIZABLE
UNIVERSALNESSES UNREVOLUTIONARY UNSAVOURINESSES UNVERIFIABILITY
VALETUDINARIANS VAPOURISHNESSES VASCULARISATION VASCULARIZATION
VASOCONSTRICTOR VASODILATATIONS VENTRILOQUIALLY VERACIOUSNESSES
VERITABLENESSES VERNACULARISING VERNACULARITIES VERNACULARIZING
VERSATILENESSES VERTICILLATIONS VESTIMENTIFERAN VEXATIOUSNESSES
VIBROFLOTATIONS VICARIOUSNESSES VICISSITUDINARY VINDICABILITIES
VINDICATIVENESS VIOLINISTICALLY VIRTUALISATIONS VIRTUALIZATIONS
VISIONARINESSES VITILITIGATIONS VITRIOLISATIONS VITRIOLIZATIONS
VIVACIOUSNESSES VIVISECTIONALLY VOLATILISATIONS VOLATILIZATIONS
VOLUNTARINESSES VORACIOUSNESSES VULNERABILITIES