There are 727 twelve-letter words containing A, C, E, M and S, https://www.bestwordlist.com/c/a/5/12letterwordswithacems.htm ACADEMICIANS ACADEMICISMS ACCLIMATISED ACCLIMATISER ACCLIMATISES ACCLIMATIZES ACCOMMODATES ACCOMPANIERS ACCOMPLISHED ACCOMPLISHER ACCOMPLISHES ACCUMBENCIES ACCUSTREMENT ACETONAEMIAS ACHIEVEMENTS ACHLAMYDEOUS ACHROMATISED ACHROMATISES ACHROMATIZES ACIDIMETRIES ACQUIREMENTS ACROMEGALICS ACROMEGALIES ACTINOMETERS ADENECTOMIES ADVANCEMENTS AERODYNAMICS AESTHETICISM AFFORCEMENTS AIRCRAFTSMEN ALYCOMPAINES AMBIVALENCES AMERCIAMENTS AMICABLENESS AMPHICOELOUS AMPHISBAENIC AMPULLACEOUS AMYLOPECTINS ANECDOTALISM ANEMOCHOROUS ANEURISMATIC ANEURYSMATIC ANTECHAMBERS ANTICLIMAXES ANTICONSUMER APPEACHMENTS ARCHDUKEDOMS ARCHESPORIUM ARMIPOTENCES ASCOMYCETOUS ASSEMBLANCES ASSEMBLAUNCE ASYMMETRICAL ATHERMANCIES ATHLETICISMS ATMOSPHERICS AXINOMANCIES AXISYMMETRIC BACHELORDOMS BACHELORISMS BACILLAEMIAS BACKSWIMMERS BACKSWORDMEN BACKWOODSMEN BACTERAEMIAS BATHOCHROMES BEACHCOMBERS BENCHWARMERS BICAMERALISM BICAMERALIST BIOCHEMICALS BIOMAGNETICS BIOMECHANICS BLACKMAILERS BLASTODERMIC BOMBACACEOUS BUTTERCREAMS CABBAGEWORMS CALLIGRAMMES CALLISTEMONS CALORIMETERS CAMARADERIES CAMELEOPARDS CAMERAPERSON CAMERAPHONES CAMIKNICKERS CAMPIMETRIES CANDELABRUMS CAPNOMANCIES CARAMELISING CARBAMIDINES CARBIMAZOLES CARBYLAMINES CARMINATIVES CARTOMANCIES CASHIERMENTS CASSIOPEIUMS CATHETERISMS CAVALIERISMS CEMENTATIONS CENTESIMALLY CENTIGRAMMES CENTIMORGANS CEREBRALISMS CHAIRWARMERS CHAMAEPHYTES CHAMBERHANDS CHAMBERLAINS CHAMBERMAIDS CHARACTERISM CHASMOGAMIES CHASTENMENTS CHASTISEMENT CHEMONASTIES CHEMOTAXISES CHILDERMASES CHIROMANCERS CHIROMANCIES CHOIRMASTERS CHOREODRAMAS CHORIAMBUSES CHORUSMASTER CHREMATISTIC CHRESTOMATHY CHROMINANCES CINEMATISING CINNAMONIEST CIRCUMSTANCE CLAMJAMFRIES CLAMMINESSES CLEISTOGAMIC CLEPTOMANIAS CLERICALISMS CLEROMANCIES CLICKSTREAMS CLIMACTERICS CLISTOGAMIES COADMINISTER COCKAMAMIEST CODOMINANCES COENENCHYMAS COFFEEMAKERS COGNOMINATES COLLEGIALISM COLLEMBOLANS COLLENCHYMAS COMEUPPANCES COMICALITIES COMMANDERIES COMMANDMENTS COMMEASURING COMMEMORATES COMMENDATORS COMMENSALISM COMMENSALITY COMMENSURATE COMMENTARIES COMMENTATORS COMMISERABLE COMMISERATED COMMISERATES COMMISERATOR COMMISSAIRES COMMISSARIES COMMONALTIES COMMONPLACES COMMUNALISED COMMUNALISER COMMUNALISES COMMUNALIZES COMMUNICATES COMPACTIFIES COMPAGINATES COMPARATIVES COMPARTMENTS COMPASSIONED COMPEARANCES COMPENSATING COMPENSATION COMPENSATIVE COMPENSATORS COMPENSATORY COMPLACENCES COMPLAISANCE COMPLIANCIES COMPLICACIES COMPORTANCES COMPULSATIVE COMRADELIEST COMRADESHIPS CONCEALMENTS CONFORMANCES CONGEALMENTS CONNUMERATES CONSERVATISM CONSUMMATELY CONSUMMATIVE CONTAINMENTS CONTAMINATES CONTEMPLANTS CONTEMPLATES CORPOREALISM COSMETICALLY COSMETICIANS COSMOGRAPHER COSMOLATRIES COUNTERMANDS COUNTERMARKS CRANIOMETERS CRANIOTOMIES CRASSAMENTUM CREAMINESSES CREATIANISMS CREATIONISMS CREMAILLERES CREMATIONISM CREMATIONIST CREMATORIUMS CRIMINALESES CRIMINALISED CRIMINALISES CRIMINALIZES CROSSMATCHED CROSSMATCHES CRYPTOGAMIES CRYPTOMERIAS CRYPTOMNESIA CURTAILMENTS CUSTOMISABLE CUSTOMIZABLE CYCLOSTOMATE DAMASCEENING DAMASCENINGS DEBAUCHMENTS DECEMVIRATES DECIMALISING DECLAMATIONS DECOMPENSATE DECOMPOSABLE DEMARCATIONS DEMOCRATISED DEMOCRATISER DEMOCRATISES DEMOCRATISTS DEMOCRATIZES DEMOGRAPHICS DEMONIACISMS DESCRAMBLERS DESCRAMBLING DEUTOPLASMIC DEUTSCHMARKS DIALECTICISM DIATOMACEOUS DICEPHALISMS DIMERCAPROLS DISCARDMENTS DISCOMEDUSAN DISCRIMINATE DISPLACEMENT DISSEMBLANCE DOMESTICABLE DOMESTICALLY DOMESTICATED DOMESTICATES DOMESTICATOR DOMICILIATES DOMINATRICES DOOMWATCHERS ECOTARIANISM EFFEMINACIES ELASMOBRANCH ELECTROGRAMS EMANCIPATORS EMASCULATING EMASCULATION EMASCULATIVE EMASCULATORS EMASCULATORY EMBARCADEROS EMBARCATIONS EMBRACEMENTS EMBROCATIONS EMPARLAUNCES EMPLACEMENTS ENCEPHALOMAS ENCHAINMENTS ENCHANTMENTS ENCHONDROMAS ENCOMPASSING ENCUMBRANCES ENHANCEMENTS EPICHEIREMAS EPICUREANISM EPISCOPALISM EROTOMANIACS ESCARMOUCHES ESCHEATMENTS EUCHROMATINS EVANGELICISM EXCLAMATIONS EXCLAMATIVES EXTRAMUSICAL FACSIMILEING FLAMBOYANCES GALACTOSEMIA GALACTOSEMIC GASOMETRICAL GASTROCNEMII GEMEINSCHAFT GEOMECHANICS GLOSSEMATICS GLUCOSAMINES GRAMINACEOUS GRAMMATICISE GREENBACKISM GYNAECOMASTS GYNAECOMASTY GYNECOMASTIA HAEMACHROMES HAEMATOCELES HAEMATOCRITS HAEMOCHROMES HAEMOCYANINS HAEMOSTATICS HAMANTASCHEN HAMMERCLOTHS HECTOGRAMMES HEMEROCALLIS HEMODYNAMICS HEMOPHILIACS HEXADECIMALS HIERARCHISMS HIEROMANCIES HOMOEOSTATIC HUMECTATIONS HYDROMANCERS HYDROMANCIES HYOSCYAMINES HYOSCYAMUSES HYPERSARCOMA IATROCHEMIST ICONOMACHIES ILLUMINANCES IMMACULACIES IMMIGRANCIES IMMODERACIES IMPEACHMENTS IMPECCANCIES IMPLICATURES IMPORTANCIES IMPRECATIONS IMPUISSANCES INCENDIARISM INCONSUMABLE INCREMATIONS INCREMENTALS INCRIMINATES INCUMBRANCES INDOMETACINS INFOMERCIALS INIMICALNESS INNUMERACIES INSECTARIUMS ISOCHEIMENAL ISODIAMETRIC ISOENZYMATIC ISOMAGNETICS ITACOLUMITES KITCHENMAIDS LACHRYMARIES LACHRYMOSELY LAMELLICORNS LEGITIMACIES LEPTOSOMATIC LEUCAEMOGENS LEUCODERMIAS LIMACOLOGIES LITHOMANCIES LOMENTACEOUS MACABERESQUE MACADAMISERS MACADAMIZERS MACERANDUBAS MACHICOLATES MACKINTOSHES MACROCYTOSES MACROGAMETES MACRONUCLEUS MACROPTEROUS MADEFACTIONS MAGISTRACIES MAGNETICIANS MAINTENANCES MAJESTICALLY MAJESTICNESS MALACOLOGIES MALEDICTIONS MALEFACTIONS MALEFACTRESS MALEFICENCES MALEVOLENCES MALFEASANCES MALIGNANCIES MALPRACTICES MAMMECTOMIES MANTELPIECES MANUFACTURES MARCESCENCES MARICULTURES MARISCHALLED MARKETPLACES MARSHLOCKSES MASCULINISED MASCULINISES MASCULINIZED MASCULINIZES MASTECTOMIES MASTERPIECES MATRIARCHIES MATRICULATES MATROCLINIES MEATPACKINGS MECHANICIANS MECHANISABLE MECHATRONICS MEDICALISING MEDIOCRACIES MEGACHURCHES MEGAPROJECTS MELANCHOLIAS MELANCHOLICS MELANCHOLIES MENDACIOUSLY MENDICANCIES MERCANTILISM MERCANTILIST MERCENARISMS MERCHANDISED MERCHANDISER MERCHANDISES MERCHANDIZES MERCHANTINGS MERCHANTRIES MERCURATIONS MERCURIALISE MERCURIALISM MERCURIALIST MERISTEMATIC MERISTICALLY MESALLIANCES MESENCEPHALA MESMERICALLY MESOAMERICAN MESOCEPHALIC MESOTHORACES MESOTHORACIC METABOLOMICS METACARPUSES METACENTRICS METACHRONISM METAFICTIONS METALLOCENES METAPHRASTIC METAPHYSICAL METAPOLITICS METAPSYCHICS METASILICATE METATHORACES METATUNGSTIC METRICATIONS MICROAMPERES MICROCAPSULE MICROCEPHALS MICROGAMETES MICROMANAGES MICROPARTIES MICROREADERS MILLOCRACIES MINICASSETTE MISALLIANCES MISALLOCATED MISALLOCATES MISCALCULATE MISCANTHUSES MISCAPTIONED MISCARRIAGES MISCATALOGED MISCATALOGUE MISCEGENATED MISCEGENATES MISCEGENATOR MISCELLANIES MISCELLANIST MISCHALLENGE MISCHANCEFUL MISCHANCIEST MISCHANNELED MISCREANCIES MISCREATIONS MISCREAUNCES MISEDUCATING MISEDUCATION MISFEASANCES MISGUIDANCES MISMATCHMENT MISPLACEMENT MISPUNCTUATE MODERATRICES MOLECATCHERS MONONUCLEARS MONOVALENCES MOTHERCRAFTS MOTORCOACHES MOUCHARABIES MOUNTENANCES MOUSTACHIOED MUCKSPREADER MULTICOSTATE MULTISULCATE MUNICIPALISE MUSCULATURES MUSEOLOGICAL MUSICALITIES MUSICIANLIER MYCETOMATOUS MYELOBLASTIC MYSTICALNESS NANOMACHINES NECROMANCERS NECROMANCIES NECROMANIACS NEMATOCYSTIC NIACINAMIDES NIGROMANCIES NOMENCLATORS NONACADEMICS NONCHEMICALS NUCLEOPLASMS OSTEOMALACIA OSTEOMALACIC OSTEOSARCOMA OSTRACODERMS OUTSCREAMING PACHYDERMIAS PACHYDERMOUS PANICMONGERS PANSPERMATIC PARACETAMOLS PARAMEDICALS PARAMOUNCIES PARCHMENTISE PEACEMAKINGS PEDANTICISMS PERFORMANCES PERICARDIUMS PERICRANIUMS PERIOSTRACUM PERISTOMATIC PERMANENCIES PERMITTANCES PLASTOMETRIC PLEIOCHASIUM PLUMULACEOUS POLICYMAKERS PRECISIANISM PREDICAMENTS PREECLAMPSIA PREMEDICATES PREROMANTICS PRIMULACEOUS PROBLEMATICS PROCTODAEUMS PROMUSCIDATE PROSENCHYMAS RACEMISATION RACHIOTOMIES RACTOPAMINES RADIOCHEMIST RAMENTACEOUS REACCLIMATES REACCUSTOMED REACTIONISMS RECLAMATIONS RECOMBINANTS RECOMMITTALS RECRIMINATES REENACTMENTS REMEMBRANCES REMONSTRANCE REPLACEMENTS RESEMBLANCES RETRACEMENTS RIFACIMENTOS ROMANTICISED ROMANTICISES ROMANTICIZES ROUTEMARCHES SABERMETRICS SACRAMENTALS SACRAMENTARY SACRAMENTING SALICYLAMIDE SALINOMETRIC SANCTIMONIES SARCENCHYMES SARCOLEMMATA SARCOMATOSES SCAMPISHNESS SCAPEGOATISM SCARAMOUCHED SCARAMOUCHES SCAREMONGERS SCATTERGRAMS SCATTERMOUCH SCHEMATISING SCHEMATIZING SCHISMATISED SCHISMATISES SCHISMATIZED SCHISMATIZES SCHMALTZIEST SCHOOLMASTER SCHWARMEREIS SCITAMINEOUS SCLERENCHYMA SCLERODERMAS SCLERODERMIA SCOPOLAMINES SCOUTMASTERS SCRIMSHANDER SCRIMSHANKED SCRIMSHANKER SCYPHISTOMAE SECTARIANISM SECTIONALISM SEISMONASTIC SEMANTICALLY SEMANTICISTS SEMAPHORICAL SEMEIOTICIAN SEMIABSTRACT SEMICIRCULAR SEMICLASSICS SEMICOLONIAL SEMICOMATOSE SEMIDETACHED SEMIMETALLIC SEMIMONASTIC SEMIMYSTICAL SEMIOFFICIAL SEMIOLOGICAL SEMIOTICALLY SEMIOTICIANS SEMITROPICAL SEPTICAEMIAS SERIOCOMICAL SERVICEWOMAN SHAMEFACEDLY SMALLCLOTHES SMARTWATCHES SMILACACEOUS SOMAESTHETIC SOMATOTENSIC SOMNIFACIENT SPECTROGRAMS SPEECHMAKERS SPEECHMAKING SPERMAPHYTIC SPERMATHECAE SPERMATHECAL SPERMATHECAS SPERMATOCELE SPERMATOCIDE SPERMATOCYTE SPERMATOZOIC SPODOMANCIES STACTOMETERS STAPEDECTOMY STERCORANISM STIMULANCIES STOMACHACHES STRETCHMARKS SUCCEDANEUMS SUPERNACULUM SUPREMACISMS SUPREMACISTS SYMPATHETICS SYSTEMATICAL SYSTEMICALLY TACHEOMETERS TACHOMETRIES TACHYMETRIES TAUROMACHIES TECHNOMANIAS TELECOMMANDS TELESMATICAL TERMAGANCIES TETRADRACHMS THALASSAEMIC THALASSEMICS THEATRICISMS THEOMACHISTS THERMOSTATIC TRACHEOSTOMY TRACKLEMENTS TRADUCEMENTS TRANSHUMANCE TRUCKMASTERS TSUNAMIGENIC TUBERCULOMAS TUMEFACTIONS UNACCUSTOMED UNCOMPOSABLE UNMECHANISED UNMECHANISES UNMECHANIZES UNSCRAMBLERS UNSYSTEMATIC VARICOTOMIES VASECTOMISED VASECTOMISES VASECTOMIZED VASECTOMIZES VERMICULATES WALLCLIMBERS WRECKMASTERS ZOOSPERMATIC