There are 771 twelve-letter words containing A, C, 2S and T, https://www.bestwordlist.com/c/a/5/12letterwordswithacsst.htm ABJECTNESSES ABSOLUTISTIC ABSORPTANCES ABSTINENCIES ABSTRACTIONS ABSTRACTIVES ABSTRACTNESS ABSTRICTIONS ACAROLOGISTS ACATALEPSIES ACCLIMATISES ACCOMPANISTS ACCURATENESS ACHROMATISES ACHROMATISMS ACOLOUTHOSES ACOUSTICIANS ACQUIESCENTS ACQUISITIONS ACTIVENESSES ADDICTEDNESS ADSCITITIOUS ADSCRIPTIONS ADULTESCENTS AESTHETICISE AESTHETICISM AESTHETICIST AFFECTEDNESS AGNOSTICISMS AHISTORICISM ANACATHARSES ANACATHARSIS ANAESTHETICS ANCESTRESSES ANILINCTUSES ANISODACTYLS ANTHRACNOSES ANTIFASCISMS ANTIFASCISTS ANTIMACASSAR ANTISCIENCES ANTISPASTICS APOLITICISMS APOSTOLICISM ARTHROSCOPES ARTOCARPUSES ASCENSIONIST ASCOMYCETOUS ASEPTICISING ASSOCIATIONS ASSUEFACTION ASTACOLOGIES ASTACOLOGIST ASTRINGENCES ASTROCOMPASS ASTROCYTOMAS ASTROHATCHES ASTRONAUTICS ASTROPHYSICS ATHLETICISMS ATHROCYTOSES ATHROCYTOSIS ATMOSPHERICS AUSCULTATORS BACKSCATTERS BACKSTABBERS BACKSTITCHES BACKSTROKERS BATHYSCAPHES BATTLESPACES BENEFACTRESS BICUSPIDATES BIOACOUSTICS BIOCATALYSES BIOCATALYSIS BIOCATALYSTS BISOCIATIONS BLACKLISTERS BLASTOCHYLES BLASTOCOELES BROADCASTERS CACTOBLASTES CACTOBLASTIS CAESPITOSELY CALENDARISTS CALISTHENICS CALLISTEMONS CANDLESTICKS CANISTERISED CANISTERISES CANISTERIZES CANOPHILISTS CAPSULATIONS CAPTAINSHIPS CAPTIOUSNESS CARILLONISTS CARPOLOGISTS CASHIERMENTS CASSITERITES CASTIGATIONS CATACAUSTICS CATACOUSTICS CATALOGUISES CATALOGUISTS CATAPHORESES CATAPHORESIS CATASTROPHES CATCHINESSES CATCHPHRASES CATECHESISES CATECHISINGS CATHETERISES CATHETERISMS CATHOLICISES CATHOLICISMS CATHOLICOSES CAUSATIONISM CAUSATIONIST CAUSTICITIES CAUTIOUSNESS CENESTHESIAS CENTRALISERS CEPHALITISES CERATOPSIANS CEREBRALISTS CEROPLASTICS CHALKSTRIPES CHANSONETTES CHARGESHEETS CHARISMATICS CHASTENESSES CHASTENMENTS CHASTISEMENT CHATTINESSES CHAUNTRESSES CHEATGRASSES CHEESESTEAKS CHEESETASTER CHEMONASTIES CHEMOTAXISES CHIASTOLITES CHIEFTAINESS CHLOROPLASTS CHOIRMASTERS CHORISATIONS CHORUSMASTER CHRISMATIONS CHRISTIANIAS CHROMOPLASTS CIRROSTRATUS CLARINETISTS CLASSICALIST CLASSICALITY CLASSICISTIC CLAVECINISTS CLEARSTORIES CLERICALISTS CLICKSTREAMS CLISTOGAMIES COASTEERINGS COENESTHESIA COLONIALISTS COMMISERATES COMMISSARIAT COMMUNALISTS COMPARATISTS COMPENSATORS CONFISCATORS CONSECRATORS CONSECTARIES CONSERVATISE CONSERVATISM CONSERVATORS CONSISTORIAL CONSISTORIAN CONSOLATIONS CONSOLIDATES CONSPIRACIST CONSPIRATORS CONSTELLATES CONSTERNATES CONSTRAINERS CONSTUPRATES CONSUMMATORS CONTRABASSES CONTRABASSOS CONTRABBASSI CONTRABBASSO CONTRARINESS CONTRASTIEST CONTREDANSES CORNSTARCHES CORPORATISES CORPORATISMS CORPORATISTS CORUSCATIONS CORYBANTISMS COSCENARISTS COSMETICIANS COSMOLATRIES COSMONAUTICS COSMOPLASTIC COTONEASTERS COTRANSDUCES COTRANSPORTS COUNTERBASES COUNTERSEALS COUNTRYSEATS CRAFTINESSES CRAFTSPERSON CRAPSHOOTERS CRASSAMENTUM CREATIANISMS CREATIONISMS CREATIONISTS CREATIVENESS CREATORSHIPS CRESCENTADES CRETACEOUSES CRIMINALISTS CRITICALNESS CRITICASTERS CROSSABILITY CROSSHATCHED CROSSHATCHES CROSSMATCHED CROSSMATCHES CROSSPATCHES CRYSTALISERS CRYSTALISING CRYSTALIZERS CRYSTALLINES CRYSTALLISED CRYSTALLISER CRYSTALLISES CRYSTALLITES CRYSTALLITIS CRYSTALLIZES CRYSTALLOIDS CURATIVENESS CURATORSHIPS CUSPIDATIONS CUSTOMISABLE CYCLISATIONS DECAPSULATES DECARTELISES DECRETALISTS DECUSSATIONS DELICATENESS DELICATESSEN DEMOCRATISES DEMOCRATISTS DESANCTIFIES DESECRATIONS DESICCATIONS DESICCATIVES DETACHEDNESS DEUTSCHMARKS DIATONICISMS DIBASICITIES DICTATRESSES DIDACTICISMS DIDACTYLISMS DISACCREDITS DISACCUSTOMS DISASSOCIATE DISCALCEATES DISCARDMENTS DISCEPTATORS DISCONSOLATE DISENTRANCES DISLOCATIONS DISSOCIALITY DISSOCIATING DISSOCIATION DISSOCIATIVE DISTANCELESS DISTRACTIONS DISTURBANCES DOCKISATIONS DODECASTYLES DOMESTICATES DRACONTIASES DRACONTIASIS DRAMATICISMS DYNASTICISMS DYSAESTHETIC ECCLESIASTIC EDUCATEDNESS ELASTICISING ELASTICITIES EMASCULATORS ENCAPSULATES ENCYSTATIONS ENTHUSIASTIC ESCAPOLOGIST ESCHEATMENTS ESTHETICIANS EUCALYPTUSES EVISCERATORS EXACTINGNESS EXPISCATIONS EXSICCATIONS EXTRINSICALS FACSIMILISTS FACTIOUSNESS FANTASTICISM FANTASTICOES FASCINATIONS FISSICOSTATE FORECASTINGS FORNICATRESS FRACTIONISES GALACTOSIDES GASTRONOMICS GASTROSCOPES GASTROSCOPIC GASTROTRICHS GATECRASHERS GESELLSCHAFT GESTICULATES GIGANTICNESS GLASSCUTTERS GLOSSEMATICS GLYCOSYLATES GRACIOSITIES GYNAECOMASTS HAEMOSTATICS HARMONICISTS HARUSPICATES HEPTARCHISTS HETEROSCIANS HEXASTICHONS HUCKSTERAGES HYDROSTATICS HYPAESTHESIC ICHTHYOSAURS INACTIVENESS INCAPSULATES INCENSATIONS INCHOATENESS INCRASSATING INCRASSATION INCRASSATIVE INOSILICATES INSECTARIUMS INTACTNESSES INTERCLASSES INTERCOSTALS INTRASPECIES IRRESISTANCE ISOMAGNETICS JUSTICIALISM JUSTICIARIES KETOACIDOSES KETOACIDOSIS KINESIATRICS LACTESCENCES LACUNOSITIES LAICISATIONS LANDSCAPISTS LANDSKNECHTS LATCHSTRINGS LECITHINASES LINECASTINGS LOGISTICIANS LOGOMACHISTS MACKINTOSHES MACROCYTOSES MACROCYTOSIS MAGISTRACIES MAJESTICNESS MALEFACTRESS MARCATISSIMO MASCULINISTS MASTECTOMIES MASTERPIECES MASTICATIONS MESOTHORACES METACARPUSES METAPSYCHICS MINICASSETTE MISALLOCATES MISCANTHUSES MISCEGENATES MISCELLANIST MISCHANCIEST MISCITATIONS MISCREATIONS MISLOCATIONS MONASTICISMS MONOCRYSTALS MUSCULATIONS MUSCULATURES MUSICALITIES MYCOPHAGISTS MYSTICALNESS NANOCRYSTALS NARCISSISTIC NECESSITATED NECESSITATES NEWSCASTINGS NIGHTCLASSES NONCONSTANTS NONSOCIALIST NYCTINASTIES OBFUSCATIONS OBSCURANTISM OBSCURANTIST OBSCURATIONS OBSECRATIONS OCTASTICHONS OCTASTICHOUS OCTOSEPALOUS ONOMASTICONS ORCHESTRATES ORCHESTRINAS OSCILLATIONS OSCULATORIES OSSIFICATION OSTEOBLASTIC OSTEOCLASTIC OSTEOPLASTIC OSTEOSARCOMA OSTRACISABLE OSTRACODERMS OUTDISTANCES OVERCASTINGS PACESETTINGS PANCRATIASTS PANPSYCHISTS PANTISOCRATS PARACENTESES PARACENTESIS PARACHUTISTS PARACROSTICS PARASTICHIES PARASTICHOUS PATCHINESSES PATRISTICISM PECTISATIONS PEDANTICISES PEDANTICISMS PESCATARIANS PESCETARIANS PETTICHAPSES PHAGOCYTISES PHAGOCYTISMS PHAGOCYTOSES PHAGOCYTOSIS PHOTOMOSAICS PHYSICALISTS PLASTICISERS PLASTICISING PLASTICITIES PLASTICIZERS PLASTICKIEST PLASTICWARES POETICALNESS POLYCRYSTALS POSTORGASMIC POSTSURGICAL POSTSYNAPTIC POSTULANCIES PRECISIANIST PRIESTCRAFTS PSYCHIATRIES PSYCHIATRIST PUNCTUALISTS PYROCLASTICS QUASICRYSTAL REACTIONISMS REACTIONISTS REACTIVENESS REBROADCASTS RESEARCHISTS RESPECTABLES RESUSCITABLE RESUSCITANTS RESUSCITATED RESUSCITATES RESUSCITATOR RHAPSODISTIC ROCKSTEADIES ROMANTICISES ROMANTICISMS ROMANTICISTS ROUGHCASTERS RUSTICATINGS RUSTICATIONS SABERMETRICS SACCULATIONS SACRAMENTALS SACRILEGISTS SACROCOSTALS SACROILIITIS SADDLECLOTHS SADISTICALLY SALTCHUCKERS SALTIMBANCOS SALTIMBOCCAS SANCTIFYINGS SANCTIMONIES SANCTIONEERS SANCTIONINGS SANCTIONLESS SANCTUARISED SANCTUARISES SANCTUARIZES SANSCULOTTES SANSCULOTTIC SANTALACEOUS SARCOMATOSES SARCOMATOSIS SATISFACTION SATISFACTORY SATISFICINGS SCABRIDITIES SCAMBAITINGS SCANTINESSES SCAPEGOATISM SCARABAEISTS SCATOLOGISTS SCATOPHAGIES SCATOPHAGOUS SCATTERGOODS SCATTERGRAMS SCATTERLINGS SCATTINESSES SCHECKLATONS SCHEMATISING SCHISMATICAL SCHISMATISED SCHISMATISES SCHISMATIZED SCHISMATIZES SCHISTOSOMAL SCHMALTZIEST SCHOLARLIEST SCHOLASTICAL SCHOOLCRAFTS SCHOOLMASTER SCINTILLATES SCISSIPARITY SCISSORTAILS SCITAMINEOUS SCOUTMASTERS SCRATCHBACKS SCRATCHCARDS SCRATCHINESS SCREENCRAFTS SCYPHISTOMAE SCYPHISTOMAS SEARCHLIGHTS SECRETARIATS SECTARIANISE SECTARIANISM SECTIONALISE SECTIONALISM SECTIONALIST SECULARISTIC SECULARITIES SEISMONASTIC SELECTORATES SEMANTICISTS SEMIABSTRACT SEMICOMATOSE SEMIMONASTIC SEMIMYSTICAL SEMIOTICIANS SENSUALISTIC SEPARATISTIC SEPARATRICES SEPTICAEMIAS SHADOWCASTED SHORTCHANGES SIDEROSTATIC SIGNIFICANTS SIGNIFICATES SIMULCASTING SINGLETRACKS SLACKTIVISMS SLACKTIVISTS SMALLCLOTHES SMARTWATCHES SOCIOPATHIES SOLECISTICAL SOLIDARISTIC SOMAESTHETIC SOMATOTENSIC SOMATOTONICS SOPHISTICATE SPACEFLIGHTS SPACIALITIES SPASMOLYTICS SPASTICITIES SPATTERDOCKS SPECIALISTIC SPECIALITIES SPECIFICATES SPECTACULARS SPECTATRICES SPECTATRIXES SPECTRALNESS SPECTROGRAMS SPECULATIONS SPECULATISTS SPEECHCRAFTS SPERMATHECAS SPHRAGISTICS SPICULATIONS SPIFFLICATES SPIROCHAETES SPORTCASTERS SPORTSCASTER STACTOMETERS STAGECOACHES STAIRCASINGS STANCHNESSES STARCHEDNESS STARFUCKINGS STATISTICIAN STAUROSCOPES STAUROSCOPIC STAYSTITCHED STAYSTITCHES STEEPLECHASE STEEPLEJACKS STEGOCARPOUS STENOCARDIAS STEPDANCINGS STERCORANISM STERCORANIST STERCORARIES STERNOCOSTAL STICKHANDLES STICKLEADERS STICKLEBACKS STIMULANCIES STIPULACEOUS STITCHCRAFTS STOCKTAKINGS STOMACHACHES STRABISMICAL STREETSCAPES STRETCHMARKS STRIDULANCES STYRACACEOUS SUBACIDITIES SUBALLOCATES SUBAPOSTOLIC SUBCELESTIAL SUBCONTRACTS SUBCUTANEOUS SUBFACULTIES SUBINDICATES SUBSECRETARY SUBSPECIALTY SUBSTRACTING SUBSTRACTION SUBSTRACTORS SUBTENANCIES SUBTRACTIONS SUCCESSANTLY SUCCUSSATION SUFFOCATINGS SUFFOCATIONS SUPERELASTIC SUPEROCTAVES SUPERPLASTIC SUPPLICAVITS SUPPORTANCES SUPRACRUSTAL SUPREMACISTS SURFCASTINGS SURREALISTIC SUSCEPTANCES SUSCITATIONS SUSTENTACULA SWITCHBLADES SWITCHBOARDS SYCOPHANTISE SYCOPHANTISH SYCOPHANTISM SYLLABICATES SYMPATHETICS SYNAESTHETIC SYNCOPATIONS SYNDACTYLIES SYNDACTYLISM SYNDACTYLOUS SYNDICALISTS SYNDICATIONS SYSTEMATICAL SYSTEMICALLY TACHYPHASIAS TACTLESSNESS TEACHERSHIPS TECHNOSPEAKS TERSANCTUSES TESTIFICATES THALASSAEMIC THALASSEMICS THALASSOCRAT THEATRICISES THEATRICISMS THEOMACHISTS THOUGHTCASTS TOBACCONISTS TOSTICATIONS TOWNSCAPINGS TOXOCARIASES TOXOCARIASIS TRACASSERIES TRACHEITISES TRAGICALNESS TRANSACTIONS TRANSCEIVERS TRANSCRIBERS TRANSDUCTORS TRANSECTIONS TRANSIENCIES TRANSLOCATES TRANSPICUOUS TRANSPIERCES TRANSURANICS TRICHINIASES TRICHINIASIS TRICHURIASES TRICHURIASIS TRITICALNESS TROPICALISES TRUCKMASTERS TSAREVITCHES TSESAREVITCH TSESAREWITCH TYPECASTINGS UNASSOCIATED UNCHASTENESS UNCHASTITIES UNCHRISTIANS UNSANCTIFIES UNSECTARIANS UNSYSTEMATIC VACANTNESSES VACATIONISTS VACATIONLESS VARICOSITIES VASCULATURES VASCULITIDES VASCULITISES VASECTOMISED VASECTOMISES VASECTOMIZES VERTICALNESS VESICATORIES VINDICATRESS VISCOELASTIC VULCANISATES WAINSCOTINGS WATCHFULNESS WATCHGLASSES WATCHSPRINGS WATERCOURSES WATERCRESSES WEATHERCASTS WELWITSCHIAS WITCHGRASSES WRECKMASTERS WRISTWATCHES ZYGOCACTUSES