There are 468 fifteen-letter words containing A, 3E and R, https://www.bestwordlist.com/c/a/5/15letterwordswithaeeer.htm
ACCESSARINESSES ACCESSORINESSES ADMIRABLENESSES ADRENALECTOMIES
ADVERSARINESSES AFTERTREATMENTS AGGREGATENESSES AGREEABLENESSES
ALLERGENICITIES ALTERNATIVENESS AMBIDEXTERITIES ANDROSTENEDIONE
ANTHROPOGENESES APPRENTICEMENTS ARCHAEOPTERYXES ASSERTIVENESSES
ATHEROSCLEROSES BALNEOTHERAPIES BAREFACEDNESSES BEARDLESSNESSES
BENZANTHRACENES BENZENECARBONYL BLETHERANSKATES BRAINLESSNESSES
BREAKABLENESSES BROKENHEARTEDLY CARPETBAGGERIES CENTRICALNESSES
CHOLESTEROLEMIA CHOLINESTERASES CLEARHEADEDNESS COLDHEARTEDNESS
COLORABLENESSES COMPLEMENTARIES COMRADELINESSES CONQUERABLENESS
CONSECRATEDNESS CONSIDERATENESS CONTEMPERATURES CONVERSABLENESS
COOPERATIVENESS CORPORATENESSES CORPOREALNESSES CORRELATIVENESS
COUNTEREXAMPLES COUNTERFEISANCE COUNTERFESAUNCE COUNTERMEASURES
CRESTFALLENNESS DAGUERREOTYPERS DAGUERREOTYPIES DANGEROUSNESSES
DEDIFFERENTIATE DEFENESTRATIONS DEGENERATIONIST DEGRADINGNESSES
DEMISEMIQUAVERS DEPARTMENTALISE DEPARTMENTALIZE DESIRABLENESSES
DESPERATENESSES DETERMINATENESS DETERMINATIVELY DETERRABILITIES
DEUTERANOMALIES DEXFENFLURAMINE DIASTEREOISOMER DISENTRANCEMENT
DISFEATUREMENTS DISHEARTENMENTS DISINTERMEDIATE DISPARATENESSES
DISTEMPERATURES DOWNHEARTEDNESS DREADLESSNESSES DREAMLESSNESSES
DRINKABLENESSES ECCLESIOLATRIES ECCREMOCARPUSES ECLAIRCISSEMENT
ELABORATENESSES ELECTROANALYSES ELECTROCHEMICAL ELECTRODIALYSES
ELECTROGRAPHIES ELECTROMAGNETIC ELECTROMETRICAL ELECTROMOTANCES
ELECTRONEGATIVE ELECTROVALENCES ELECTROVALENTLY ELEUTHERODACTYL
ELEUTHEROMANIAS ELEUTHEROPHOBIA EMBRACINGNESSES EMPIRICALNESSES
ENDEARINGNESSES ENDURABLENESSES ENFRANCHISEMENT ENGRAINEDNESSES
ENTEROBACTERIAL ENTEROBACTERIUM ENTEROGASTRONES ENTEROHEPATITIS
ENTREPRENEURIAL ENUMERABILITIES EPEIROGENICALLY EPHEMERALNESSES
EPHEMEROPTERANS EQUIPONDERANCES ESTRANGEDNESSES ETHEREALISATION
ETHEREALIZATION EVANGELISTARIES EVERLASTINGNESS EXACERBESCENCES
EXAGGERATEDNESS EXECRABLENESSES EXEMPLARINESSES EXPERIENTIALISM
EXPERIENTIALIST EXPERIMENTALISE EXPERIMENTALISM EXPERIMENTALIST
EXPERIMENTALIZE EXPERIMENTATION EXPERIMENTATIVE EXTEMPORARINESS
FAVORABLENESSES FEATHERBEDDINGS FEATHERSTITCHED FEATHERSTITCHES
FEATURELESSNESS FERROMANGANESES FILTRABLENESSES FORMATIVENESSES
FORTUNATENESSES FRANGIBLENESSES GENTLEWOMANLIER GINGERBREADIEST
GLYCERALDEHYDES GOVERNMENTALISE GOVERNMENTALIZE GRACELESSNESSES
GRANDIOSENESSES HAEMACYTOMETERS HAEMOCYTOMETERS HALFHEARTEDNESS
HARDHEARTEDNESS HEADMASTERLIEST HEADMISTRESSIER HEARTBROKENNESS
HEARTLESSNESSES HEARTSICKNESSES HEARTSOMENESSES HERESIOGRAPHERS
HERESIOGRAPHIES HERESTHETICIANS HERMENEUTICALLY HETEROCERCALITY
HETERONORMATIVE HETEROSCEDASTIC HETEROSEXUALITY HEXACHLORETHANE
HEXACHLOROPHENE HONORABLENESSES HYPERAESTHESIAS HYPERAGGRESSIVE
HYPERVENTILATED HYPERVENTILATES ILLIBERALNESSES IMPERMEABLENESS
IMPERVIABLENESS IMPREGNABLENESS INALTERABLENESS INAPPREHENSIBLE
INCURABLENESSES INDETERMINACIES INDETERMINATELY INERRABLENESSES
INGRAINEDNESSES INHERITABLENESS INNUMERABLENESS INOPERATIVENESS
INSEPARABLENESS INSUPERABLENESS INTEMPERATENESS INTERCHANGEABLE
INTERCHANGEMENT INTERCOLLEGIATE INTERCORRELATED INTERCORRELATES
INTERGENERATION INTERPENETRABLE INTERPENETRATED INTERPENETRATES
INTERPERCEPTUAL INTERPERMEATING INTERTANGLEMENT INTERVALOMETERS
INTERWEAVEMENTS INTOLERABLENESS INTRICATENESSES IRASCIBLENESSES
IRREDEEMABILITY IRREFUTABLENESS IRREMOVABLENESS IRREPARABLENESS
IRREVOCABLENESS IRRITABLENESSES ITERATIVENESSES KATATHERMOMETER
KINDERGARTENERS KINDHEARTEDNESS KINESITHERAPIES LEGERDEMAINISTS
LIONHEARTEDNESS LUCRATIVENESSES MACRENCEPHALIES MAGNETOELECTRIC
MARVELOUSNESSES MASTERFULNESSES MEASURELESSNESS MECHANORECEPTOR
MEGAVERTEBRATES MEMORABLENESSES MENISPERMACEOUS MERCENARINESSES
MERCURIALNESSES METATHEORETICAL MISAPPREHENSIVE MISERABLENESSES
MISMEASUREMENTS MOMENTARINESSES MOUNTEBANKERIES NEARSIGHTEDNESS
NECESSARINESSES NEFARIOUSNESSES NEOARSPHENAMINE NEOCONSERVATIVE
NEUROECTODERMAL NONCREDENTIALED NONEXPERIMENTAL NONHETEROSEXUAL
NORMATIVENESSES NORTHEASTERLIES NORTHEASTERNERS NOVOCENTENARIES
OCTOCENTENARIES OPENHEARTEDNESS OPERATIVENESSES OVERACCENTUATED
OVERACCENTUATES OVERACHIEVEMENT OVERALERTNESSES OVERASSESSMENTS
OVERBEARINGNESS OVERCENTRALISED OVERCENTRALISES OVERCENTRALIZED
OVERCENTRALIZES OVERCOMPENSATED OVERCOMPENSATES OVEREAGERNESSES
OVEREARNESTNESS OVERENTERTAINED OVEREXAGGERATED OVEREXAGGERATES
OVEREXPECTATION OVEREXTRAPOLATE OVEREXUBERANTLY OVERGENERALISED
OVERGENERALISES OVERGENERALIZED OVERGENERALIZES OVERHASTINESSES
OVERMANAGEMENTS OVERORCHESTRATE OVERSPECIALISED OVERSPECIALISES
OVERSPECIALIZED OVERSPECIALIZES OVERZEALOUSNESS PAINTERLINESSES
PAMPHLETEERINGS PARALLELEPIPEDA PARALLELEPIPEDS PARTHENOGENESES
PARTHENOGENESIS PARTHENOGENETIC PECTINESTERASES PENETRABILITIES
PENETRATIVENESS PERGAMENTACEOUS PERIHEPATITISES PERIPHERALITIES
PERMANENTNESSES PERMEABLENESSES PERVASIVENESSES PLEASURABLENESS
PNEUMATOMETRIES PRAYERFULNESSES PREADOLESCENCES PREANAESTHETICS
PREANNOUNCEMENT PREARRANGEMENTS PRECIPITATENESS PREDATORINESSES
PREDETERMINABLE PREDICTABLENESS PREEXPERIMENTAL PREFERABILITIES
PREFERENTIALISM PREFERENTIALIST PREFERENTIALITY PREKINDERGARTEN
PREMATURENESSES PREPERFORMANCES PREPONDERANCIES PREPRESIDENTIAL
PRESBYTERIANISE PRESBYTERIANIZE PRESENTABLENESS PRESENTIALITIES
PREVALENTNESSES PRINTABLENESSES PROCREATIVENESS PROXIMATENESSES
PSEUDOMEMBRANES PYRETOTHERAPIES QUARRELSOMENESS QUATERCENTENARY
QUINCENTENARIES QUINGENTENARIES RADIOTELEMETERS RADIOTELEMETRIC
RADIOTELEPHONED RADIOTELEPHONES REACCELERATIONS READVERTISEMENT
READVERTIZEMENT REAPPRAISEMENTS RECEIVABILITIES RECHOREOGRAPHED
RECONCEPTUALISE RECONCEPTUALIZE RECONTEXTUALISE RECONTEXTUALIZE
RECONVALESCENCE RECOVERABLENESS RECTIPETALITIES REDEEMABILITIES
REDETERMINATION REDOUBTABLENESS REESTABLISHMENT REFRACTOMETRIES
REFRANGIBLENESS REFRIGERATORIES REGARDFULNESSES REMEDIABILITIES
REMEMBERABILITY REMOVABLENESSES REPEATABILITIES REPRESENTATIONS
REPRESENTATIVES RESECTABILITIES RESPECTABILISED RESPECTABILISES
RESPECTABILIZED RESPECTABILIZES RESPECTABLENESS RETRIEVABLENESS
RETROACTIVENESS RETROPERITONEAL REVEALABILITIES REVEALINGNESSES
REVERBERATORIES REVOCABLENESSES RIGHTABLENESSES ROLLERCOASTERED
ROUNDHEADEDNESS SCLEROTHERAPIES SEARCHINGNESSES SEAWORTHINESSES
SECONDARINESSES SEDENTARINESSES SEMITERRESTRIAL SEPARABLENESSES
SEROPREVALENCES SERVICEABLENESS SESQUICENTENARY SLEDGEHAMMERING
SOFTHEARTEDNESS SOUTHEASTERLIES SOUTHEASTERNERS SPELEOTHERAPIES
SPERMATOGENESES SPERMATOGENESIS SPERMATOGENETIC SPHAEROSIDERITE
SPHERICALNESSES SUPERABLENESSES SUPERCALENDERED SUPERELEVATIONS
SUPERLATIVENESS SUPERNUMERARIES SUPERSPECTACLES SUPPLEMENTARIES
TEMERARIOUSNESS TEMPERABILITIES TEMPERAMENTALLY TEMPERATENESSES
TEMPORARINESSES TENDERHEARTEDLY TERRESTRIALNESS TETRAETHYLLEADS
TETRAMETHYLLEAD THERMAESTHESIAS THERMOBAROMETER THERMOREGULATED
THERMOREGULATES THERMOREMANENCE THERMOTHERAPIES THORACOCENTESES
TOLERABLENESSES TRACEABLENESSES TRACKLESSNESSES TRACTABLENESSES
TRANSCENDENCIES TRANSIENTNESSES TREACHEROUSNESS TREASONABLENESS
TRUEHEARTEDNESS UNALTERABLENESS UNAPPREHENSIBLE UNCERTAINNESSES
UNCREATEDNESSES UNDEREMPHASISED UNDEREMPHASISES UNDEREMPHASIZED
UNDEREMPHASIZES UNDERGRADUETTES UNDERHANDEDNESS UNDERSTATEMENTS
UNDESIRABLENESS UNEARTHLINESSES UNENDURABLENESS UNGENTLEMANLIER
UNGUARDEDNESSES UNINTERPRETABLE UNIVERSALNESSES UNLEARNEDNESSES
UNNECESSARINESS UNRECOMMENDABLE UNUTTERABLENESS UNWEARIEDNESSES
UTTERABLENESSES VENERABLENESSES VERACIOUSNESSES VERITABLENESSES
VERSATILENESSES VESTIMENTIFERAN WARMHEARTEDNESS WASTERFULNESSES
WATERLESSNESSES WEARISOMENESSES WEATHERLINESSES WRONGHEADEDNESS