There are 599 twelve-letter words containing A and 2M, https://www.bestwordlist.com/c/a/3/12letterwordswithamm.htm ABNORMALISMS ACADEMICISMS ACCOMMODABLE ACCOMMODATED ACCOMMODATES ACCOMMODATOR ACHROMATISMS ADMONISHMENT AEROEMBOLISM AGRAMMATICAL AGROSTEMMATA ALLOMORPHISM AMALGAMATING AMALGAMATION AMALGAMATIVE AMALGAMATORS AMBULANCEMAN AMBULANCEMEN AMERCIAMENTS AMETABOLISMS AMMONIATIONS AMMUNITIONED AMORTISEMENT AMORTIZEMENT AMPEROMETRIC AMPHETAMINES AMPHISTOMOUS AMPHITHECIUM ANAGRAMMATIC ANAMORPHISMS ANEMOMETRIES ANIMALCULISM ANTIFEMINISM ANTIHUMANISM ANTIJAMMINGS ANTIMNEMONIC ARITHMOMANIA ARITHMOMETER ARMAMENTARIA ASTIGMATISMS ASYMMETRICAL ASYMPTOMATIC ATTEMPERMENT AUTOIMMUNITY AUTOMOBILISM AUTOMORPHISM AXISYMMETRIC BACKGAMMONED BACKSWIMMERS BICAMERALISM BIMETALLISMS BLAMESTORMED BOHEMIANISMS BOMBARDMENTS BREASTSUMMER CALCEAMENTUM CALLIGRAMMES CAMPIMETRIES CAMPODEIFORM CENTIGRAMMES CHAMBERMAIDS CHASMOGAMIES CHASMOGAMOUS CHROMATICISM CHROMATOGRAM CHROMONEMATA CLAMJAMFRIES CLAMJAMPHRIE CLAMMINESSES CLOMIPRAMINE COCKAMAMIEST COLUMBARIUMS COMANAGEMENT COMMANDEERED COMMANDERIES COMMANDINGLY COMMANDMENTS COMMEASURING COMMEMORABLE COMMEMORATED COMMEMORATES COMMEMORATOR COMMENDATION COMMENDATORS COMMENDATORY COMMENSALISM COMMENSALITY COMMENSURATE COMMENTARIAL COMMENTARIAT COMMENTARIES COMMENTATING COMMENTATION COMMENTATORS COMMERCIALLY COMMINATIONS COMMISERABLE COMMISERATED COMMISERATES COMMISERATOR COMMISSAIRES COMMISSARIAL COMMISSARIAT COMMISSARIES COMMISSIONAL COMMITTEEMAN COMMONALTIES COMMONPLACED COMMONPLACES COMMONWEALTH COMMUNALISED COMMUNALISER COMMUNALISES COMMUNALISMS COMMUNALISTS COMMUNALIZED COMMUNALIZER COMMUNALIZES COMMUNICABLE COMMUNICABLY COMMUNICANTS COMMUNICATED COMMUNICATEE COMMUNICATES COMMUNICATOR COMMUNITAIRE COMMUTATIONS COMPARTMENTS COMPLEMENTAL COMPLIMENTAL COMPRIMARIOS CONSUMMATELY CONSUMMATING CONSUMMATION CONSUMMATIVE CONSUMMATORS CONSUMMATORY CRASSAMENTUM CREMATIONISM CREMATORIUMS CUPRAMMONIUM CYTOMEMBRANE DARMSTADTIUM DEMAGOGUISMS DEMIMONDAINE DEMONIACISMS DEMONIANISMS DEMONOMANIAS DEPROGRAMMED DEPROGRAMMER DEPROGRAMMES DIAGRAMMABLE DIAGRAMMATIC DIAMAGNETISM DICHROMATISM DISARMAMENTS DISMASTMENTS DRAMATICISMS DURALUMINIUM DYNAMOMETERS DYNAMOMETRIC ELEMENTALISM EMBARQUEMENT EMBATTLEMENT EMBLAZONMENT EMBLEMATICAL EMBLEMATISED EMBLEMATISES EMBLEMATISTS EMBLEMATIZED EMBLEMATIZES EMBRACEMENTS EMBRANCHMENT EMMENAGOGUES EMOLUMENTARY EMOTIONALISM EMPANELMENTS EMPLACEMENTS EMPYREUMATIC ENDAMAGEMENT ENFRAMEMENTS ENJAMBEMENTS ENTHYMEMATIC ENTRAMMELING ENTRAMMELLED EPIGRAMMATIC EPITHALAMIUM EUDAEMONISMS EUDAIMONISMS FLAMMABILITY FLAMMIFEROUS FLAMMULATION FLIMFLAMMERS FLIMFLAMMERY FLIMFLAMMING FUNAMBULISMS GAMESMANSHIP GAMESOMENESS GAMMERSTANGS GAMOTROPISMS GEMMOLOGICAL GEMMULATIONS GEOMAGNETISM GOURMANDISMS GRAMMALOGUES GRAMMATICISE GRAMMATICISM GRAMMATICIZE GRAMMATOLOGY GYMNATORIUMS HAEMACHROMES HAEMANGIOMAS HAEMATEMESES HAEMATEMESIS HAEMOCHROMES HAEMODYNAMIC HAMMERCLOTHS HAMMERHEADED HAMMERSTONES HARMONIUMIST HARMONOGRAMS HARMONOMETER HECTOGRAMMES HELIANTHEMUM HELLGRAMMITE HELMSMANSHIP HEMANGIOMATA HEMODYNAMICS HEXAGRAMMOID HIEROGRAMMAT HOMEOTHERMAL HOMOLOGUMENA HOMOPLASMIES HOMOTHALLISM IMMACULACIES IMMACULATELY IMMANENTISMS IMMANENTISTS IMMATERIALLY IMMATURENESS IMMATURITIES IMMEASURABLE IMMEASURABLY IMMEDIATISMS IMMEMORIALLY IMMENSURABLE IMMETHODICAL IMMIGRANCIES IMMIGRATIONS IMMISERATING IMMISERATION IMMODERACIES IMMODERATELY IMMODERATION IMMORALITIES IMMORTALISED IMMORTALISER IMMORTALISES IMMORTALIZED IMMORTALIZER IMMORTALIZES IMMOVABILITY IMMUNISATION IMMUNIZATION IMMUNOASSAYS IMMUTABILITY IMPANELMENTS IMPEACHMENTS IMPEDIMENTAL IMPERIALISMS IMPERMANENCE IMPERMANENCY IMPOSTHUMATE IMPOSTUMATED IMPOSTUMATES INCOMMUTABLE INCOMMUTABLY INFLAMMABLES INFLAMMATION INFLAMMATORY INSTAGRAMMED JACKHAMMERED KATZENJAMMER LAMMERGEIERS LAMMERGEYERS LAMPADEDROMY LAMPADOMANCY LYMPHANGIOMA LYMPHOMATOID LYMPHOMATOUS MACADAMISERS MACADAMISING MACADAMIZERS MACADAMIZING MACROCLIMATE MACROGAMETES MADEMOISELLE MAGISTERIUMS MAGNETOMETER MAGNETOMETRY MAILGRAMMING MAIMEDNESSES MAINSTREAMED MAINTOPMASTS MAISTERDOMES MALAPROPISMS MALFORMATION MALIMPRINTED MALTREATMENT MAMILLATIONS MAMMALOGICAL MAMMALOGISTS MAMMECTOMIES MAMMILLARIAS MAMMILLATION MAMMILLIFORM MAMMOGRAPHIC MANAGEMENTAL MANDARINISMS MANOMETRICAL MANORIALISMS MANUMISSIONS MARCATISSIMO MARCONIGRAMS MARGINALISMS MARIMBAPHONE MARKSMANSHIP MARSHMALLOWS MARSHMALLOWY MARTINETISMS MASTECTOMIES MASTERMINDED MATCHMAKINGS MATCHMARKING MATERIALISMS MATERNALISMS MATHEMATICAL MATHEMATISED MATHEMATISES MATHEMATIZED MATHEMATIZES MAXIMISATION MAXIMIZATION MAYSTERDOMES MEALYMOUTHED MEASUREMENTS MECAMYLAMINE MEDIAEVALISM MEDICAMENTAL MEDICAMENTED MEDIEVALISMS MEGALOMANIAC MEGALOMANIAS MEGASTARDOMS MEGAVITAMINS MELODRAMATIC MEMBRANOUSLY MEMORABILITY MEMORIALISED MEMORIALISER MEMORIALISES MEMORIALISTS MEMORIALIZED MEMORIALIZER MEMORIALIZES MEMORISATION MEMORIZATION MENINGIOMATA MEPROBAMATES MERCANTILISM MERCENARISMS MERCURIALISM MERISTEMATIC MERRYMAKINGS MESMERICALLY MESOAMERICAN MESOGASTRIUM MESOGNATHISM MESOTHELIOMA METABOLOMICS METACHRONISM METACOMPUTER METAGNATHISM METAMATERIAL METAMORPHISM METAMORPHIST METAMORPHOSE METAMORPHOUS METASOMATISM METEMPIRICAL METEOROGRAMS METHANAMIDES METHANOMETER METHENAMINES METHYLAMINES METRONOMICAL MICROAMPERES MICROANATOMY MICROCLIMATE MICROGAMETES MICROMACHINE MICROMANAGED MICROMANAGER MICROMANAGES MICROPAYMENT MICROPROGRAM MICROTOMICAL MIDSHIPMATES MILLENARISMS MILLESIMALLY MILLIAMPERES MILLIGRAMMES MILLILAMBERT MIMEOGRAPHED MIMOGRAPHERS MIMOGRAPHIES MINIMALISTIC MINIMISATION MINIMIZATION MISALIGNMENT MISALLOTMENT MISASSEMBLED MISASSEMBLES MISDEMEANANT MISDEMEANING MISDEMEANORS MISDEMEANOUR MISEMPHASISE MISEMPHASIZE MISERABILISM MISERABLISMS MISESTIMATED MISESTIMATES MISFORMATION MISINFORMANT MISMARRIAGES MISMATCHMENT MISMEASURING MISPLACEMENT MISPROGRAMED MISSTATEMENT MISSUMMATION MISTREATMENT MITHRIDATISM MNEMONICALLY MOCKUMENTARY MOMENTANEOUS MONASTICISMS MONEYMAKINGS MONOCHROMASY MONOCHROMATE MONOCHROMATS MONODRAMATIC MONOFILAMENT MONOGAMISTIC MONOGAMOUSLY MONOGRAMMERS MONOGRAMMING MONOMANIACAL MONOMETALLIC MONOMETRICAL MONOMYARIANS MONOTHALAMIC MONUMENTALLY MOVIEMAKINGS MUCKAMUCKING MULTICHAMBER MULTIMEGATON MULTINOMIALS MULTINOMINAL MULTIVITAMIN MUNICIPALISM MURMURATIONS MYCETOMATOUS MYCODOMATIUM MYCOPLASMATA MYOFILAMENTS MYTHOMANIACS MYXEDEMATOUS NEONOMIANISM NINNYHAMMERS NOCTAMBULISM NONALUMINIUM NONCOMMITTAL NONFLAMMABLE NONIMMIGRANT NONMAMMALIAN NONMETAMERIC NORMOTHERMIA NOUMENALISMS NUMISMATISTS NUMMULATIONS NYMPHOMANIAC NYMPHOMANIAS OMMATOPHORES OMNISHAMBLES OMPHALOMANCY OVERCRAMMING PALUDAMENTUM PAMPELMOOSES PAMPELMOUSES PANDAEMONIUM PANDEMONIUMS PANSPERMISMS PANTOMIMICAL PANTOMIMISTS PARAMORPHISM PENTAMERISMS PERMEAMETERS PHONOGRAMMIC PLASMALEMMAS PLASMODESMAS PLASMOGAMIES PLASMOSOMATA POLYMASTISMS PRAGMATICISM PRASEODYMIUM PROGRAMMABLE PROGRAMMATIC PROGRAMMINGS PROGYMNASIUM PROTHALAMIUM PSAMMOPHILES PSAMMOPHYTES PSAMMOPHYTIC RADIOMIMETIC REAMENDMENTS RECOMMITTALS REMAINDERMAN REMAINDERMEN REMEMBERABLE REMEMBERABLY REMEMBRANCER REMEMBRANCES REPROGRAMMED REPROGRAMMES RHABDOMYOMAS RHEUMATISMAL ROMANTICISMS SARCOLEMMATA SEMIBASEMENT SEMICOMATOSE SEMIDIAMETER SEMIDOMINANT SEMIMETALLIC SEMIMONASTIC SEMIMYSTICAL SEMIPALMATED SHAMATEURISM SHUNAMITISMS SLEDGEHAMMER SMALMINESSES SMARMINESSES SOMATOMEDINS SOMATOPLASMS SOMNAMBULANT SOMNAMBULARY SOMNAMBULATE SOMNAMBULISM SOMNAMBULIST SPERMAGONIUM SPHYGMOGRAMS STAMMERINGLY STOMATODAEUM SUBMAXIMALLY SUBMICROGRAM SUMMARISABLE SUMMARIZABLE SUMMERSAULTS SUPREMACISMS SUPREMATISMS SYMMETALISMS SYMMETALLISM SYMPTOMATISE SYMPTOMATIZE SYSTEMATISMS TAUTOMERISMS TELECOMMANDS TELEGRAMMING TEMPERAMENTS TERMITARIUMS TETRAMERISMS TIMBROMANIAC TIMBROMANIAS TIMESTAMPING TRANSFORMISM TRIGRAMMATIC TRINOMIALISM TRIUMPHALISM UNCOMMERCIAL UNPROGRAMMED UNTRAMMELLED VERUMONTANUM VOLTAMMETERS WINDJAMMINGS XERANTHEMUMS XYLOBALSAMUM YELLOWHAMMER ZOOMAGNETISM