There are 648 thirteen-letter words containing A, C, E, M and S, https://www.bestwordlist.com/c/a/5/13letterwordswithacems.htm
ACADEMICALISM ACATAMATHESIA ACCIDENTALISM ACCLIMATISERS ACCLIMATIZERS
ACCOMPLISHERS ACCOUCHEMENTS ACCOUPLEMENTS ACCOUSTREMENT ACCOUTERMENTS
ACCOUTREMENTS ACCUSTREMENTS ACTINOMETRIES ACTINOMYCETES ACTINOMYCOSES
ADMINICULATES ADRENOCHROMES AEROMECHANICS AEROMEDICINES AESTHETICISMS
AGRICHEMICALS AGROCHEMICALS ALCHEMISTICAL ALEMBICATIONS ALEXIPHARMICS
ALPHANUMERICS AMARANTACEOUS AMBIVALENCIES AMICABILITIES AMNIOCENTESES
AMNIOCENTESIS AMPHICTYONIES AMYGDALACEOUS ANDROCENTRISM ANDRODIOECISM
ANECDOTALISMS ANISOMETROPIC ANNOUNCEMENTS ANTHELMINTICS ANTIMECHANIST
ANTIMNEMONICS ANTISEPTICISM ANTISYMMETRIC ARCHEOMETRIES ARCHIPHONEMES
AROMATICITIES ARTHRECTOMIES ASCERTAINMENT ASSEMBLAUNCES ASTROMETRICAL
ATMOSPHERICAL AUTOCOMPLETES AUTOEROTICISM AUTOSCHEDIASM BACKSWORDSMEN
BASIDIOMYCETE BEACHCOMBINGS BENCHMARKINGS BIBLIOMANCIES BICAMERALISMS
BICAMERALISTS BIMETALLISTIC BIOMETRICIANS BIOSYSTEMATIC BISYMMETRICAL
BLASTOMYCOSES BOTANOMANCIES BRACHYPTERISM BROMELIACEOUS BUREAUCRATISM
CABINETMAKERS CACKERMANDERS CAESAROPAPISM CALORIMETRIES CAMERAPERSONS
CAMPANOLOGERS CAMPANOLOGIES CAMPHORACEOUS CAPELLMEISTER CARPETMONGERS
CATECHUMENISM CATHETOMETERS CATHIODERMIES CENTUMVIRATES CEPHALOMETERS
CEPHALOTOMIES CEREMONIALISM CEREMONIALIST CERULOPLASMIN CHAENOMELESES
CHALAZOGAMIES CHAMPIONESSES CHARACTERISMS CHASTISEMENTS CHEIROMANCERS
CHEIROMANCIES CHEMOAUTROPHS CHEMOSURGICAL CHIMNEYBOARDS CHIMNEYBREAST
CHLAMYDOSPORE CHLORENCHYMAS CHONDROSAMINE CHORUSMASTERS CHREMATISTICS
CHRESTOMATHIC CHRISMATORIES CHROMATICNESS CHROMATOLYSES CHRYSANTHEMUM
CINEMATHEQUES CIRCUMAMBAGES CIRCUMGYRATES CIRCUMNUTATES CIRCUMROTATES
CIRCUMSTANCED CIRCUMSTANCES CIRCUMSTELLAR CLAMJAMPHRIES CLAMOROUSNESS
CLAVICEMBALOS CLEISTOGAMIES CLEISTOGAMOUS CLEPTOMANIACS CLIMATOLOGIES
CLISHMACLAVER CLOMIPRAMINES CLOTRIMAZOLES COADMINISTERS COASTGUARDMEN
COLLEGIALISMS COLUMNARITIES COMANAGEMENTS COMBATIVENESS COMICALNESSES
COMMANDERSHIP COMMEASURABLE COMMEMORATORS COMMENDATIONS COMMENSALISMS
COMMENSURABLE COMMENSURABLY COMMENTARIATS COMMENTATIONS COMMERCIALESE
COMMERCIALISE COMMERCIALISM COMMERCIALIST COMMISERATING COMMISERATION
COMMISERATIVE COMMISERATORS COMMONALITIES COMMONWEALTHS COMMUNALISERS
COMMUNALITIES COMMUNALIZERS COMMUNICATEES COMMUNITAIRES COMPACTEDNESS
COMPACTNESSES COMPANIONLESS COMPASSIONATE COMPELLATIONS COMPELLATIVES
COMPENSATIONS COMPLACENCIES COMPLAISANCES COMPLEXATIONS COMPLIANTNESS
COMPRESSIONAL COMRADELINESS CONCEPTUALISM CONCERTMASTER CONCOMITANCES
CONCREMATIONS CONDEMNATIONS CONGLOMERATES CONGRESSWOMAN CONSERVATISMS
CONTEMPLATIST CONTEMPLATORS CONTUMACITIES CORPOREALISMS COSMECEUTICAL
COSMOCHEMICAL COSMOGRAPHERS COSMOGRAPHIES COSMOTHETICAL COSTARDMONGER
COUNTERCHARMS COUNTERCLAIMS COUNTERIMAGES COUNTERSTREAM CRAFTSMANLIKE
CRANIECTOMIES CRANIOGNOMIES CRANIOMETRIES CRANIOMETRIST CREDENTIALISM
CREMATIONISMS CREMATIONISTS CRIMINALITIES CRITHOMANCIES CRYPTOMNESIAS
CUSTOMARINESS CYTOMEMBRANES DECALCOMANIAS DECOMPENSATED DECOMPENSATES
DECRIMINALISE DECUMULATIONS DEMOCRATISERS DEMOCRATISING DEMOCRATIZERS
DEMONOCRACIES DETERMINACIES DIALECTICISMS DIATHERMACIES DIATOMICITIES
DICHLAMYDEOUS DISACCUSTOMED DISAFFIRMANCE DISCOMEDUSANS DISCRIMINABLE
DISCRIMINATED DISCRIMINATES DISPLACEMENTS DISSEMBLANCES DOCUMENTALIST
DOCUMENTARIES DOCUMENTARISE DOCUMENTARIST DODECAPHONISM DOMESTICATING
DOMESTICATION DOMESTICATIVE DOMESTICATORS DOSIMETRICIAN ECCREMOCARPUS
ECONOMISATION ECOTARIANISMS ECUMENICALISM ELASMOBRANCHS EMANCIPATIONS
EMASCULATIONS EMBRACINGNESS EMBRANCHMENTS EMPIRICALNESS ENCOMIASTICAL
ENCOMPASSMENT ENCROACHMENTS ENCUMBRANCERS ENTOMOSTRACAN ENTRANCEMENTS
EPICUREANISMS EPISCOPALISMS EPISTEMICALLY ETHEROMANIACS EUDAEMONISTIC
EUDAIMONISTIC EVANGELICISMS FIDEICOMMISSA FLAMBOYANCIES FRANCHISEMENT
FRUMENTACEOUS GALACTOMETERS GALACTOSAEMIA GALACTOSAEMIC GALACTOSAMINE
GALACTOSEMIAS GASTRECTOMIES GASTROCNEMIUS GASTROMANCIES GEMEINSCHAFTS
GEODYNAMICIST GEOMETRICIANS GIMCRACKERIES GONADECTOMIES GRAMMATICISED
GRAMMATICISES GRAMMATICIZES GREENBACKISMS GYNAECOMASTIA GYNECOMASTIAS
GYROCOMPASSES HAEMODYNAMICS HAEMOPHILIACS HANDCRAFTSMEN HEMATOBLASTIC
HEMICHORDATES HEMIPARASITIC HEMISPHERICAL HEPATECTOMIES HISTAMINERGIC
HISTOCHEMICAL HOCHMAGANDIES HOMOSCEDASTIC HYPERSARCOMAS HYPOCALCEMIAS
HYPOGLYCEMIAS HYPSOMETRICAL IATROCHEMISTS IDIOMATICNESS IMMANENTISTIC
IMMARCESCIBLE IMPERIALISTIC IMPERMANENCES IMPORTUNACIES INCENDIARISMS
INCOMPATIBLES INCOMPLIANCES INCUMBRANCERS INDOMETHACINS INIMICALITIES
INTEMPERANCES INTERCOMPARES INTERMUSCULAR ISMATICALNESS ISOBAROMETRIC
ISOCHEIMENALS ISOMETRICALLY KERATECTOMIES KLEPTOMANIACS LAMINECTOMIES
LOWERCLASSMAN LOWERCLASSMEN LUMBERJACKETS LUMBRICALISES MACHIAVELIANS
MACROCLIMATES MAGNETOSTATIC MAGNIFICENCES MAGNOLIACEOUS MAJOLICAWARES
MALACOPHILIES MALICIOUSNESS MANNERISTICAL MANUFACTORIES MANUFACTURERS
MARCHIONESSES MASCULINENESS MASCULINITIES MASTERCLASSES MASTICATORIES
MASTOIDECTOMY MATCHLESSNESS MATERIALISTIC MATERNALISTIC MATHEMATICISE
MATHEMATICISM MATRIARCHATES MECAMYLAMINES MECHANICALISM MECHANISATION
MEDICAMENTOUS MEDIEVALISTIC MEGACEPHALIES MEGACEPHALOUS MEGALOBLASTIC
MEGALOCARDIAS MEGALOMANIACS MEGASTRUCTURE MELANCHOLIACS MELANCHOLIOUS
MELANOCHROOUS MELODRAMATICS MEMBRANACEOUS MERCANTILISMS MERCANTILISTS
MERCENARINESS MERCERISATION MERCHANDISERS MERCHANDISING MERCHANDIZERS
MERCURIALISED MERCURIALISES MERCURIALISMS MERCURIALISTS MERCURIALIZES
MERCURIALNESS MERITOCRACIES MESATICEPHALY MESENCEPHALIC MESENCEPHALON
MESOCEPHALICS MESOCEPHALIES MESOCEPHALISM MESOCEPHALOUS MESSIANICALLY
METACERCARIAS METACHRONISMS METACOMPUTERS METAPHYSICIAN METAPHYSICISE
METAPHYSICIST METAPHYSICIZE METAPSYCHICAL METASILICATES METHACRYLATES
MICROANALYSES MICROBALANCES MICROCAPSULES MICROCASSETTE MICROCLIMATES
MICROFINANCES MICROGRANITES MICROGRAPHERS MICROGRAPHIES MICROMACHINES
MICROMANAGERS MICROPARASITE MICROPAYMENTS MINICASSETTES MISADVERTENCE
MISAPPRECIATE MISARTICULATE MISCALCULATED MISCALCULATES MISCATALOGUED
MISCATALOGUES MISCEGENATING MISCEGENATION MISCEGENATORS MISCELLANEOUS
MISCELLANISTS MISCHALLENGES MISCHANNELING MISCHANNELLED MISCLASSIFIED
MISCLASSIFIES MISEDUCATIONS MISGOVERNANCE MISMATCHMENTS MISOBSERVANCE
MISPLACEMENTS MISPUNCTUATED MISPUNCTUATES MISTRANSCRIBE MONEYCHANGERS
MONOCHROMATES MONOVALENCIES MOUNTENAUNCES MUCKSPREADERS MUCKSPREADING
MUCOCUTANEOUS MULTIACCESSES MULTIAGENCIES MULTICAMPUSES MULTICHANNELS
MULTIPLICATES MULTISPECTRAL MULTIVALENCES MUNICIPALISED MUNICIPALISES
MUNICIPALIZES MUSCULARITIES MUSICALNESSES MUSICIANLIEST MUSICOTHERAPY
MUSSELCRACKER MYCETOPHAGOUS MYCOPLASMOSES MYOCARDITISES NANOCOMPOSITE
NEOCAPITALISM NEOCLASSICISM NEOPLASTICISM NEUROMUSCULAR NICOTINAMIDES
NOMENCLATURES NONSYSTEMATIC NUCLEOPLASMIC NYMPHAEACEOUS OCCIDENTALISM
OLEANDOMYCINS OLFACTOMETERS ONEIROMANCERS ONEIROMANCIES ONYCHOMANCIES
OSTEOMALACIAL OSTEOMALACIAS OSTEOSARCOMAS OUTPLACEMENTS OVARIECTOMIES
OVERCRAMMINGS OVERDRAMATICS OVERMEDICATES PANCREOZYMINS PARAMOUNTCIES
PARARESCUEMAN PARARESCUEMEN PARCHMENTIEST PARCHMENTISED PARCHMENTISES
PARCHMENTIZES PERIOSTRACUMS PERMACULTURES PESSIMISTICAL PHARMACEUTICS
PHARMACEUTIST PHARMACOPEIAS PHLEGMAGOGICS PHOTOMACHINES PICROCARMINES
PNEUMOGASTRIC POLYCYTHEMIAS POSTVASECTOMY PRECISIANISMS PREDOMINANCES
PREECLAMPSIAS PROSENCHYMATA PROSTATECTOMY PSYCHOMACHIES RACEMISATIONS
RACEMIZATIONS RADIOCHEMISTS REACCLIMATISE REACCUSTOMING REACTIONARISM
READMITTANCES REATTACHMENTS RECOMPENSABLE RECRIMINATORS REFLECTOGRAMS
REMEMBRANCERS REMONSTRANCES REPUBLICANISM RHABDOMANCERS RHABDOMANCIES
RHINOSCLEROMA SACCHARIMETER SACCHARIMETRY SACCHAROMETER SACCHAROMETRY
SACCHAROMYCES SACERDOTALISM SACRAMENTALLY SALICYLAMIDES SALPINGECTOMY
SARMENTACEOUS SCALPELLIFORM SCANDALMONGER SCAPEGOATISMS SCATTEROMETER
SCHEMATICALLY SCHLUMBERGERA SCHOOLMASTERS SCHWARMERISCH SCLERENCHYMAS
SCLERODERMATA SCLERODERMIAS SCLEROMALACIA SCRIMSHANDERS SCRIMSHANDIED
SCRIMSHANDIES SCRIMSHANKERS SECTARIANISMS SECTIONALISMS SEISMOGRAPHIC
SEISMOLOGICAL SEMEIOLOGICAL SEMEIOTICALLY SEMEIOTICIANS SEMIABSTRACTS
SEMIAUTOMATIC SEMICARBAZIDE SEMICARBAZONE SEMICLASSICAL SEMICONSONANT
SEMIDETACHEDS SEMIEMPIRICAL SEMIOCHEMICAL SEMIOFFICIALS SEMIPARASITIC
SEMIPOLITICAL SEMIPORCELAIN SEMITONICALLY SHOCKUMENTARY SIMARUBACEOUS
SOMATOPLEURIC SOMNAMBULANCE SOMNIFACIENTS SPEECHMAKINGS SPERMATICALLY
SPERMATOCELES SPERMATOCIDAL SPERMATOCIDES SPERMATOCYTES SPERMATOGENIC
SPERMATOTHECA STAGECOACHMAN STAGECOACHMEN STERCORANISMS SULFACETAMIDE
SUPERCOLUMNAR SUPERCRIMINAL SUPERROMANTIC SUPRAMOLECULE SURCHARGEMENT
SUSTENTACULUM SYMMETRICALLY SYMPATHECTOMY SYMPATHETICAL SYNAPOSEMATIC
SYSTEMATICIAN TACHEOMETRIES TECHNOMANIACS TELEFACSIMILE TEPHROMANCIES
TETRADRACHMAS THALASSAEMICS THEATRICALISM THERMOPLASTIC THERMOSTATICS
THORACOTOMIES TRACHEOTOMIES TRAGICOMEDIES TRANSCRIPTOME TRANSHUMANCES
TRANSMITTANCE TRICHOMONASES TROCHEAMETERS UNATHLETICISM UNCOMPENSATED
UNCONSUMMATED UNDERCLASSMAN UNDERCLASSMEN UNDOMESTICATE UNICAMERALISM
UNICAMERALIST UNIMPORTANCES UNMACADAMISED UNMECHANISING UNMUSICALNESS
UNSYMMETRICAL UNSYMPATHETIC UPPERCLASSMAN UPPERCLASSMEN VAGINECTOMIES
VASECTOMISING VASECTOMIZING VERNACULARISM VISCOMETRICAL VOUCHSAFEMENT
VRAISEMBLANCE WHIMSICALNESS WOODCRAFTSMEN