There are 452 thirteen-letter words containing A, U and Y, https://www.bestwordlist.com/c/a/3/13letterwordswithauy.htm
ACOTYLEDONOUS ACQUIESCENTLY ACQUIESCINGLY ACQUIRABILITY ACQUISITIVELY
ACRIMONIOUSLY ADJUSTABILITY ADUMBRATIVELY ADVENTUROUSLY AGRANULOCYTES
ALUMINOTHERMY AMBISEXUALITY AMYGDALACEOUS ANACHRONOUSLY ANDROGYNOUSLY
ANFRACTUOSITY ANISOPHYLLOUS ANONYMOUSNESS ANTIAUTHORITY ANTISEXUALITY
APPROPINQUITY APTITUDINALLY ATTITUDINALLY ATTRIBUTIVELY AUDIOVISUALLY
AUTHENTICALLY AUTOBIOGRAPHY AUTOCATALYSED AUTOCATALYSES AUTOCATALYSIS
AUTOCATALYTIC AUTOCATALYZED AUTOCATALYZES AUTOMAGICALLY AUTOMATICALLY
AUTONOMICALLY AUTOPOLYPLOID AUTOSTABILITY AYUNTAMIENTOS BEAUTYBERRIES
BEHAVIOURALLY BIMOLECULARLY BLASPHEMOUSLY BRACHYPTEROUS BUOYANTNESSES
BURGLARIOUSLY BUTYRALDEHYDE CACOPHONOUSLY CALCULABILITY CALCULATINGLY
CALYCANTHUSES CARNIVOROUSLY CASUISTICALLY CENSURABILITY CENTRIFUGALLY
CHRYSANTHEMUM CIRCUMGYRATED CIRCUMGYRATES CIRCUMJACENCY COAGULABILITY
COLLOQUIALITY COLOURABILITY COMMENSURABLY COMMUNICATORY COMMUNIONALLY
COMMUTABILITY COMMUTATIVELY COMMUTATIVITY COMPUTABILITY CONCEPTUALITY
CONCLUSIONARY CONDYLOMATOUS CONFABULATORY CONFUSABILITY CONJECTURABLY
CONJECTURALLY CONNATURALITY CONSANGUINITY CONTRACTUALLY CONTRARIOUSLY
CONVULSIONARY COUNTERPLAYED COUNTERPLAYER CULTIVABILITY CURVILINEALLY
CURVILINEARLY CYBERSQUATTER CYLINDRACEOUS DAGUERREOTYPE DAGUERREOTYPY
DEMIURGICALLY DENTICULATELY DEUTERANOMALY DEVOLUTIONARY DIALYPETALOUS
DICHLAMYDEOUS DISGRACEFULLY DISHONOURABLY DISPURVEYANCE DISPUTABILITY
DISPUTATIVELY DISQUALIFYING DISTASTEFULLY DOCUMENTARILY DUALISTICALLY
DUPLICABILITY DYSFUNCTIONAL EDUCATABILITY EDUCATIONALLY EFFICACIOUSLY
EMPHYSEMATOUS EMPYREUMATISE EMPYREUMATIZE ENCAUSTICALLY ENCOURAGINGLY
ENUMERABILITY ENUNCIATIVELY EQUIDISTANTLY EQUILATERALLY EQUILIBRATORY
EQUINOCTIALLY ERYSIPELATOUS EXCLUDABILITY EXHAUSTLESSLY EXPOSTULATORY
EXTENUATINGLY EXTRUDABILITY FACULTATIVELY FASCICULATELY FAUNISTICALLY
FISSIPAROUSLY FLIRTATIOUSLY FORMULAICALLY FOUNDATIONARY FRUSTRATINGLY
FUNAMBULATORY FUNCTIONALITY FUNDAMENTALLY GEMMIPAROUSLY GENITOURINARY
GESTICULATORY HALFSERIOUSLY HALLUCINATORY HEURISTICALLY HEXADACTYLOUS
HOMOSEXUALITY HONOURABILITY HUBRISTICALLY HUMILIATINGLY HYALURONIDASE
HYDRAULICALLY HYDRAULICKING HYDROCEPHALUS HYDROMEDUSANS HYDROSOMATOUS
HYDROSULPHATE HYPERACUITIES HYPERAROUSALS HYPERCAUTIOUS HYPERSURFACES
HYPERURBANISM HYPERURICEMIA HYPOPITUITARY HYPOSULPHATES HYSTERANTHOUS
ICHTHYOFAUNAE ICHTHYOFAUNAL ICHTHYOFAUNAS ICHTHYOSAURUS ILLOCUTIONARY
IMMUNOTHERAPY IMPERTURBABLY IMPORTUNATELY INCULPABILITY INDISSUADABLY
INDIVIDUALITY INEDUCABILITY INEFFECTUALLY INEXHAUSTIBLY INFLUENTIALLY
INFURIATINGLY INOCULABILITY INSINUATINGLY INSTINCTUALLY INSUPPORTABLY
INTEGUMENTARY INTERSEXUALLY INTRAOCULARLY INTRAVENOUSLY INTUITIONALLY
INVOLUNTARILY ITHYPHALLUSES JUDGEMENTALLY JUDGMATICALLY JUSTIFICATORY
LANGUISHINGLY LARYNGISMUSES LATITUDINALLY MAGNANIMOUSLY MATRICULATORY
MEASURABILITY MEASURELESSLY MENSURABILITY MONODACTYLOUS MONUMENTALITY
MOUNTAINOUSLY MOUNTEBANKERY MULTIPARTYISM MULTIPOLARITY MULTIRACIALLY
MULTISYLLABIC MULTITUDINARY MUSICOTHERAPY MUTAGENICALLY MYCETOPHAGOUS
MYCOBACTERIUM MYXOEDEMATOUS NONDURABILITY NONREGULATORY NUCLEONICALLY
NUMISMATOLOGY NUTRITIONALLY NYMPHAEACEOUS OECUMENICALLY OMNIFARIOUSLY
OMNISEXUALITY OUTSTANDINGLY OVERCAREFULLY OVERZEALOUSLY PARAMYXOVIRUS
PARASEXUALITY PARTICULARITY PENINSULARITY PENULTIMATELY PERAMBULATORY
PERDURABILITY PERMUTABILITY PHYLLOPHAGOUS PLAYFULNESSES PNEUMATICALLY
PNEUMATOLYSES PNEUMATOLYSIS PNEUMATOLYTIC PNEUMATOMETRY POLYADELPHOUS
POLYBUTADIENE POLYDACTYLOUS POLYGALACEOUS POLYGONACEOUS POLYTHALAMOUS
POLYURETHANES PRASEODYMIUMS PRAYERFULNESS PREAMBULATORY PRECAUTIONARY
PRECOPULATORY PREJUDICIALLY PREQUALIFYING PRESBYACOUSES PRESBYACOUSIS
PROGYMNASIUMS PROTUBERANTLY PRUDENTIALITY PSEUDOMARTYRS PUNISHABILITY
PURGATORIALLY PURITANICALLY PUSILLANIMITY PYROSULPHATES QUADRATICALLY
QUADRENNIALLY QUADRINGENARY QUADRIVALENCY QUADRUPLICITY QUALIFICATORY
QUALITATIVELY QUARRELSOMELY QUARRYMASTERS QUASICRYSTALS QUINCENTENARY
QUINCUNCIALLY QUINGENTENARY RADICULOPATHY RECTANGULARLY REFUNDABILITY
REPROACHFULLY RETURNABILITY REVOLUTIONARY RHEUMATICALLY RUDIMENTARILY
SANGUINOLENCY SATURNALIANLY SCEUOPHYLACIA SCEUOPHYLAXES SCORBUTICALLY
SEQUENTIALITY SHOCKUMENTARY SITUATIONALLY SOUTHEASTERLY SPATHIPHYLLUM
SPECTACULARLY SPECULATIVELY SPONTANEOUSLY SQUANDERINGLY SQUEEZABILITY
STIMULATINGLY SUBCLINICALLY SUBCULTURALLY SUBMARGINALLY SUBORDINATELY
SUBSPECIALITY SUBSTANTIALLY SUBSTANTIVELY SUBSTANTIVITY SUBTROPICALLY
SUBVENTIONARY SUBVERSIONARY SUFFOCATINGLY SULFONYLUREAS SULPHONYLUREA
SUPERACTIVITY SUPERFICIALLY SUPERHIGHWAYS SUPERHUMANITY SUPERLATIVELY
SUPERLOYALIST SUPERMAJORITY SUPERNORMALLY SUPERNUMERARY SUPERORDINARY
SUPERPHYSICAL SUPPLEMENTARY SURVIVABILITY SYLVICULTURAL TAUTOLOGOUSLY
TAUTOSYLLABIC TELAUTOGRAPHY TEMERARIOUSLY TETRADYNAMOUS THAUMATOLATRY
TOURISTICALLY TRANSEXUALITY TRANSFUSIVELY TRANSLUCENTLY TRANSLUCIDITY
TRAUMATICALLY TRAUMATONASTY TREACHEROUSLY TRIANGULARITY TRIANGULATELY
TUBERCULATELY TYRANNOSAURID TYRANNOSAURUS TYRANNOUSNESS ULTRAPHYSICAL
ULTRAROYALIST ULTRAVIRILITY UNACCOUNTABLY UNAMBIGUOUSLY UNAMBITIOUSLY
UNAPPEALINGLY UNAPPROVINGLY UNASSERTIVELY UNASSIMILABLY UNBEAUTIFULLY
UNCANONICALLY UNCHRISTIANLY UNCOMBATIVELY UNCOMFORTABLY UNCOMMENDABLY
UNCONCEIVABLY UNCONFORMABLY UNCONQUERABLY UNCUSTOMARILY UNDEMANDINGLY
UNDERACTIVITY UNDERHANDEDLY UNDERLAYMENTS UNDERPAYMENTS UNDERSTATEDLY
UNDEVIATINGLY UNEMOTIONALLY UNEMPIRICALLY UNEMPLOYABLES UNENDEARINGLY
UNEQUIVOCABLY UNEQUIVOCALLY UNESSENTIALLY UNEXPLAINABLY UNFALTERINGLY
UNFAMILIARITY UNFASHIONABLY UNFORESEEABLY UNFORGETTABLY UNFORTUNATELY
UNGAINSAYABLE UNGENTLEMANLY UNHEALTHFULLY UNILATERALITY UNIMPEACHABLY
UNIMPORTANTLY UNIPARENTALLY UNJUSTIFIABLY UNKNOWABILITY UNMALICIOUSLY
UNMENTIONABLY UNMISTAKEABLY UNMITIGATEDLY UNNECESSARILY UNORIGINALITY
UNPERCEIVABLY UNPLEASURABLY UNPRACTICALLY UNPREDICTABLY UNPUNCTUALITY
UNQUALIFIEDLY UNREADABILITY UNREASONINGLY UNRECLAIMABLY UNRECOVERABLY
UNRECYCLABLES UNRELIABILITY UNREPENTANTLY UNREWARDINGLY UNSALEABILITY
UNSALVAGEABLY UNSANCTIFYING UNSERVICEABLY UNSOCIABILITY UNSPIRITUALLY
UNSTARTLINGLY UNSTEADFASTLY UNSUITABILITY UNSURPASSABLY UNSUSTAINABLY
UNSYMMETRICAL UNSYMPATHETIC UNTHRIFTYHEAD UNWARRANTABLY UNWARRANTEDLY
UNWORKABILITY UPGRADABILITY VALUATIONALLY VAPOURABILITY VERNACULARITY
VOLUNTARYISMS VOLUNTARYISTS VULNERABILITY XYLOBALSAMUMS YUPPIFICATION
ZEUGMATICALLY ZYGODACTYLOUS