There are 405 fifteen-letter words containing 2A, P, S and T, https://www.bestwordlist.com/c/a/5/15letterwordswithaapst.htm
ACCEPTABILITIES ACCOUNTANTSHIPS ACHONDROPLASTIC ACROPARESTHESIA
ACTINOTHERAPIES ADAPTABLENESSES ALLOTETRAPLOIDS ALPHABETISATION
AMINOPEPTIDASES ANISOTROPICALLY ANTAPHRODISIACS ANTHROPOLATRIES
ANTHROPOPATHIES ANTHROPOPATHISM ANTHROPOPHAGIES ANTHROPOPHAGOUS
ANTHROPOPHOBIAS ANTIAPHRODISIAC ANTICAPITALISMS ANTICAPITALISTS
ANTIDEPRESSANTS ANTINEOPLASTICS ANTIPERISTALSES ANTIPERISTALSIS
ANTIPERISTALTIC ANTIPERSPIRANTS ANTIREPUBLICANS ANTISEPARATISTS
ANTISPECULATION ANTISPECULATIVE ANTITRANSPIRANT APOCALYPTICISMS
APOLITICALITIES APOPHTHEGMATISE APOPHTHEGMATIST APOTHEGMATISING
APPEALABILITIES APPLICABILITIES APPROPRIATENESS ARCHAEOPTERYXES
ARCHIEPISCOPATE AROMATHERAPISTS ARTERIOGRAPHIES ASTROPHOTOGRAPH
ASTROPHYSICALLY ATMOSPHERICALLY AUTOBIOGRAPHERS AUTOBIOGRAPHIES
AUTORADIOGRAPHS AUTOTETRAPLOIDS BACTERIOPHAGIES BACTERIOPHAGOUS
BALNEOTHERAPIES BATRACHOPHOBIAS BIOSTRATIGRAPHY BIPARTISANSHIPS
BIPOLARISATIONS BIPOLARIZATIONS BLAXPLOITATIONS BRACHYTHERAPIES
CAPITALISATIONS CAPITALIZATIONS CARPETBAGGERIES CARPOMETACARPUS
CASTANOSPERMINE CATHODOGRAPHERS CATHODOGRAPHIES CEPHALOTHORACES
CEPHALOTHORAXES CHALCOGRAPHISTS CHANNELOPATHIES CHAPTALISATIONS
CHAPTALIZATIONS CLAUSTROPHILIAS CLAUSTROPHOBIAS CLIMATOGRAPHIES
COMMANDANTSHIPS COMPARABILITIES COMPARATIVENESS COMPASSIONATELY
COMPASSIONATING CONTEMPORANEANS CONTRAPUNTALIST CRYPTAESTHESIAS
CRYSTALLOGRAPHY CYTOPLASMICALLY DACTYLOGRAPHERS DACTYLOGRAPHIES
DEPARTMENTALISE DEPARTMENTALISM DEPOLARISATIONS DEPOLARIZATIONS
DERMATOGRAPHIAS DERMATOGRAPHIES DERMATOPLASTIES DEXAMPHETAMINES
DIAPHRAGMATITIS DIAPHRAGMITISES DIASTROPHICALLY DISAPPLICATIONS
DISAPPROBATIONS DISAPPROPRIATED DISAPPROPRIATES DISCAPACITATING
DISPARATENESSES DISPASSIONATELY DRAUGHTSMANSHIP ECOCATASTROPHES
EMANCIPATIONIST ENDOPARASITISMS EPIGRAMMATISERS EPIGRAMMATISING
EPIGRAMMATIZERS ESEMPLASTICALLY EVAPORABILITIES EXPANDABILITIES
GALACTOPOIETICS GALVANOPLASTIES GALVANOTROPISMS GRAPHITISATIONS
GRAPHITIZATIONS HEADMASTERSHIPS HEPARINISATIONS HEPARINIZATIONS
HOMOPLASTICALLY HOMOTRANSPLANTS HOSPITALISATION HOSPITALIZATION
HYDROXYAPATITES HYPERAESTHESIAS HYPERCATABOLISM HYPERNATRAEMIAS
HYPERPARASITISM HYPERSALIVATION HYPOSTASISATION HYPOSTASIZATION
HYPOSTATISATION HYPOSTATIZATION IMPALPABILITIES IMPARTIALNESSES
IMPASSABILITIES IMPLACABILITIES IMPRACTICALNESS IMPROVISATIONAL
IMPROVISATORIAL INAPPRECIATIONS INCAPACITATIONS INSPIRATIONALLY
INTERPAROXYSMAL JUXTAPOSITIONAL LAPIDIFICATIONS LIPOGRAMMATISMS
LIPOGRAMMATISTS LYMPHOSARCOMATA MAGISTRATESHIPS MALAPPROPRIATES
MALPRESENTATION MASSOTHERAPISTS MESATICEPHALIES MESATICEPHALOUS
METALLOGRAPHERS METALLOGRAPHIES METALLOGRAPHIST MISACCEPTATIONS
MISAPPLICATIONS MISAPPRECIATING MISAPPRECIATION MISAPPRECIATIVE
MISAPPROPRIATED MISAPPROPRIATES MULTIPARAMETERS NEPHROBLASTOMAS
NONENCAPSULATED NONPARTICIPANTS NONPARTISANSHIP NONPARTIZANSHIP
NONSPECTACULARS NUCLEOPLASMATIC OPERATIONALISMS OPERATIONALISTS
OPTIMALISATIONS OPTIMALIZATIONS ORGANOGRAPHISTS ORGANOPHOSPHATE
ORGANOTHERAPIES OSTEOPATHICALLY OVERCAPITALISED OVERCAPITALISES
OVERCAPITALIZES PAINSTAKINGNESS PALAEBIOLOGISTS PALAEOBIOLOGIST
PALAEOBOTANISTS PALAEOECOLOGIST PALAEOGRAPHISTS PALAEOMAGNETISM
PALAEOMAGNETIST PALAEONTOLOGIES PALAEONTOLOGIST PALAEOZOOLOGIST
PALATABLENESSES PALATALISATIONS PALATALIZATIONS PALEOMAGNETISMS
PALEOMAGNETISTS PANOPHTHALMITIS PANTHEISTICALLY PANTISOCRATICAL
PANTISOCRATISTS PANTOPRAGMATICS PARABOLISATIONS PARABOLIZATIONS
PARAGRAMMATISTS PARALINGUISTICS PARAMETRISATION PARANORMALITIES
PARASEXUALITIES PARASITICALNESS PARASITISATIONS PARASITIZATIONS
PARASITOLOGICAL PARASITOLOGISTS PARASYMPATHETIC PARLIAMENTARISM
PARTHENOCARPIES PARTHENOCARPOUS PARTICIPATORIES PARTICULARISERS
PARTICULARISING PARTICULARISTIC PARTICULARITIES PARTICULARIZERS
PARTURIFACIENTS PASTEURISATIONS PASTEURIZATIONS PATENTABILITIES
PATERFAMILIASES PATRIALISATIONS PATRIALIZATIONS PATRIARCHALISMS
PATRIFOCALITIES PENTADACTYLISMS PERGAMENTACEOUS PERISTALTICALLY
PERSONALISATION PERSONALIZATION PHANTASMAGORIAL PHANTASMAGORIAS
PHANTASMAGORIES PHANTASMALITIES PHARMACEUTICALS PHARMACOGNOSIST
PHARMACOGNOSTIC PHARMACOLOGISTS PHARMACOPOEISTS PHARMACOPOLISTS
PHOSPHATISATION PHOSPHATIZATION PHTHALOCYANINES PLAGIOSTOMATOUS
PLAINCLOTHESMAN PLANTAGINACEOUS PLASMOLYTICALLY PLASTICISATIONS
PLASTICIZATIONS PLATINOCYANIDES PLURALISTICALLY POLYUNSATURATED
POLYUNSATURATES POPULARISATIONS POPULARIZATIONS POSTAPOCALYPSES
POSTAPOCALYPTIC POSTCONSONANTAL POSTDEVALUATION POSTGRADUATIONS
POSTIRRADIATION POSTMILLENARIAN POSTULATIONALLY POSTVACCINATION
PRACTICABLENESS PRACTICALNESSES PRAGMATICALNESS PRAGMATISATIONS
PRAGMATIZATIONS PREANAESTHETICS PREARRANGEMENTS PREDESTINARIANS
PREFABRICATIONS PREINSTALLATION PREMANUFACTURES PRESYNAPTICALLY
PROCRASTINATING PROCRASTINATION PROCRASTINATIVE PROCRASTINATORS
PROCRASTINATORY PROLETARIANISED PROLETARIANISES PROLETARIANISMS
PROLETARIANIZES PROLETARIANNESS PROPAGABILITIES PROTHONOTARIATS
PROTOSPATHAIRES PROTOSPATHARIUS PRUSSIANISATION PRUSSIANIZATION
PSEUDAESTHESIAS PSYCHIATRICALLY PURITANICALNESS RADICULOPATHIES
RADIOAUTOGRAPHS RADIOTELEGRAPHS RADIOTHERAPISTS REAPPRAISEMENTS
RECAPITULATIONS REIMPLANTATIONS REPAIRABILITIES REPEATABILITIES
REPOLARISATIONS REPOLARIZATIONS REPRIVATISATION SAPONIFICATIONS
SAPROPHYTICALLY SAUROPTERYGIANS SEMIPARASITISMS SEMITRANSPARENT
SEPTUAGENARIANS SLUMPFLATIONARY SPATIALISATIONS SPATIALIZATIONS
SPECIALISATIONS SPECIALIZATIONS SPERMATOBLASTIC SPERMATORRHOEAS
SPHAEROCRYSTALS SPIROCHAETAEMIA SPREADABILITIES STAPHYLOPLASTIC
STAPHYLORRHAPHY STEGANOGRAPHERS STEGANOGRAPHIES STEGANOGRAPHIST
STEGOCEPHALIANS STEREOGRAPHICAL STIGMATOPHILIAS STOMATOPLASTIES
STRATIGRAPHICAL STRATIGRAPHISTS STRATOSPHERICAL SUBPROLETARIATS
SULPHACETAMIDES SULPHATHIAZOLES SUPERABUNDANTLY SUPERADDITIONAL
SUPERANNUATIONS SUPERBUREAUCRAT SUPEREXALTATION SUPERNATIONALLY
SUPERNATURALISE SUPERNATURALISM SUPERNATURALIST SUPERNATURALIZE
SUPERPARASITISM SUPERSATURATING SUPERSATURATION SUPRANATIONALLY
SYCOPHANTICALLY SYMPATHETICALLY SYMPTOMATICALLY SYNAPOSEMATISMS
TELAUTOGRAPHIES TETRASPORANGIUM THALASSOGRAPHER THALASSOGRAPHIC
THALASSOTHERAPY THANATOGRAPHIES THORACOPLASTIES TRANSCRIPTIONAL
TRANSPARENTISED TRANSPARENTISES TRANSPARENTIZED TRANSPARENTIZES
TRANSPARENTNESS TRANSPIRATIONAL TRANSPLANTATION TRANSPORTATIONS
TRANSPOSABILITY TRANSPOSITIONAL TROPICALISATION TRYPANOSOMIASES
TRYPANOSOMIASIS ULTRACREPIDATES ULTRASONOGRAPHY UNAPOSTOLICALLY
UNAPPRECIATIONS UNCOMPASSIONATE UNCOMPLAISANTLY UNDERCAPITALISE
UNPRACTICALNESS UNSPECTACULARLY UPGRADABILITIES VAPOURABILITIES
XENOTRANSPLANTS