There are 376 fifteen-letter words containing A, M, R and 2S, https://www.bestwordlist.com/c/a/5/15letterwordswithamrss.htm
ABSORPTIOMETERS ABSTRACTIONISMS ACRIMONIOUSNESS ADMINISTRATIONS
ADMIRABLENESSES AERODYNAMICISTS AGGRANDISEMENTS AGRIBUSINESSMAN
AGRIBUSINESSMEN ALLELOMORPHISMS AMBASSADORSHIPS AMORPHOUSNESSES
ANAMORPHOSCOPES ANDROMONOECISMS ANTHROPOPHUISMS ANTILIBERALISMS
ANTIMILITARISMS ANTIMILITARISTS ANTIMONARCHISTS ANTIQUARIANISMS
ANTIRADICALISMS APHELIOTROPISMS ARCHAEOMETRISTS AROMATHERAPISTS
ARRONDISSEMENTS ASTRODYNAMICIST BIOREGIONALISMS BLAMEWORTHINESS
BREATHARIANISMS BREMSSTRAHLUNGS CARAMELISATIONS CARCINOSARCOMAS
CASTANOSPERMINE CASTRAMETATIONS CENTENARIANISMS CENTRIPETALISMS
CHEMOTHERAPISTS CHOLESTYRAMINES CHORDAMESODERMS CHROMATICNESSES
CHROMATOLOGISTS CHROMATOSPHERES CIRCUMSTANTIALS CLAMOROUSNESSES
COCHAIRMANSHIPS COMFORTABLENESS COMMENSURATIONS COMMISSARYSHIPS
COMMISSIONAIRES COMPARATIVENESS COMRADELINESSES CONFORMABLENESS
CONSERVATORIUMS CONSIMILARITIES CONVERSATIONISM COUNTERMEASURES
CRUCIVERBALISMS CUSTOMARINESSES DEMISEMIQUAVERS DEMORALISATIONS
DERMATOMYOSITIS DERMATOPHYTOSES DERMATOPHYTOSIS DERMATOPLASTIES
DETERMINATENESS DIAPHRAGMITISES DIASTEREOISOMER DICHROMATICISMS
DISAFFIRMATIONS DISAFFORESTMENT DISARRANGEMENTS DISCIPLINARIUMS
DISCOMBOBERATES DISCOURAGEMENTS DISCRIMINATIONS DISEMBARKATIONS
DISEMBARRASSING DISENCUMBRANCES DISENTHRALMENTS DISENTRAINMENTS
DISFEATUREMENTS DISHARMONIOUSLY DISHEARTENMENTS DISINFORMATIONS
DISSIMILARITIES DISTEMPERATURES DRAUGHTSMANSHIP DREAMLESSNESSES
ECCREMOCARPUSES ECLAIRCISSEMENT EGALITARIANISMS EMBRACINGNESSES
EMPIRICALNESSES ENDOPARASITISMS EPHEMERALNESSES EPIGRAMMATISERS
EXEMPLARINESSES EXTEMPORARINESS FERRIMAGNETISMS FERROMAGNETISMS
FERROMANGANESES FIDEICOMMISSARY FLEXITARIANISMS FORISFAMILIATES
FORMATIVENESSES FRAGMENTARINESS GALVANOTROPISMS GEOMETRISATIONS
GLAMOROUSNESSES GRAMMATICALNESS GRAMMATICASTERS GRAMMATOLOGISTS
HEADMASTERLIEST HEADMASTERSHIPS HEADMISTRESSIER HEARTSOMENESSES
HEMOCHROMATOSES HEMOCHROMATOSIS HETEROTHALLISMS HOMOCHROMATISMS
HOMOTRANSPLANTS HYPERPARASITISM HYPERSTIMULATES HYPOCHONDRIASMS
IMAGINARINESSES IMMISERISATIONS IMMISERIZATIONS IMPARTIALNESSES
IMPERMEABLENESS IMPERSONALISING IMPERSONALITIES IMPERVIABLENESS
IMPORTUNATENESS IMPRACTICALNESS IMPREGNABLENESS IMPROVISATRICES
IMPROVISATRIXES IMPROVVISATORES INCREMENTALISMS INCREMENTALISTS
INFORMATIVENESS INNUMERABLENESS INSPIRATIONISMS INSTRUMENTALISM
INSTRUMENTALIST INTEMPERATENESS INTERACTIONISMS INTERSEXUALISMS
INTRANSIGENTISM INTRANSMISSIBLE IRREMOVABLENESS LEGERDEMAINISTS
LIBERTARIANISMS LIPOGRAMMATISMS LIPOGRAMMATISTS MACROSTRUCTURES
MAGISTERIALNESS MAGISTRATESHIPS MALADROITNESSES MARSHMALLOWIEST
MARVELOUSNESSES MASSOTHERAPISTS MASTERFULNESSES MATERFAMILIASES
MATRIARCHALISMS MEASURABILITIES MEASURELESSNESS MEGASPOROPHYLLS
MEMORABLENESSES MENISPERMACEOUS MENSURABILITIES MERCENARINESSES
MERCURIALNESSES METACHROMATISMS MICROAGGRESSION MICROAGGRESSIVE
MICROAGGRESSORS MICROPULSATIONS MICROSATELLITES MILITARISATIONS
MILLENARIANISMS MILLIONAIRESSES MINERALISATIONS MINISTERIALISTS
MISAPPREHENSION MISAPPREHENSIVE MISAPPROPRIATES MISARRANGEMENTS
MISATTRIBUTIONS MISCELLANARIANS MISCHARACTERISE MISCORRELATIONS
MISERABLENESSES MISGOVERNAUNCES MISINFORMATIONS MISMEASUREMENTS
MISORIENTATIONS MISREGISTRATION MISTRANSCRIBING MISTRANSLATIONS
MOMENTARINESSES MONGRELISATIONS MONOCHROMATISMS MONOSACCHARIDES
MONOUNSATURATES MULTIRACIALISMS MUSICOTHERAPIES NARCOTERRORISMS
NECESSARIANISMS NEOCONSERVATISM NEPHROBLASTOMAS NEUROANATOMISTS
NIGHTMARISHNESS NONCHARISMATICS NONRANDOMNESSES NORMATIVENESSES
OMNIFARIOUSNESS OPERATIONALISMS OSMOREGULATIONS OUTDOORSMANSHIP
OVERADJUSTMENTS OVERASSESSMENTS OVERCOMPENSATES OVEREMPHASISING
OVERENTHUSIASMS OVERESTIMATIONS PARAGRAMMATISTS PARAJOURNALISMS
PARAMYXOVIRUSES PATERFAMILIASES PATRIARCHALISMS PERIPATETICISMS
PERMANENTNESSES PERMEABLENESSES PHALLOCENTRISMS PHANTASMAGORIAS
PHANTASMAGORIES PHARMACOGNOSIES PHARMACOGNOSIST PHARMACOLOGISTS
PHARMACOPOEISTS PHARMACOPOLISTS PLETHYSMOGRAPHS POCOCURANTEISMS
POLYCHROMATISMS POLYMERISATIONS POSTMASTERSHIPS POSTSTIMULATORY
PRAGMATICALNESS PRAGMATISATIONS PREMATURENESSES PRESBYTERIANISM
PRESENTATIONISM PROBABILIORISMS PROCELEUSMATICS PROFESSIONALISM
PROLETARIANISMS PROSENCHYMATOUS PROSTATECTOMIES PROXIMATENESSES
PSEUDOMEMBRANES PSILANTHROPISMS PYRAMIDOLOGISTS QUARRELSOMENESS
QUARTERMISTRESS QUATTROCENTISMS RADIOSTRONTIUMS REACTIONARYISMS
REAPPRAISEMENTS REESTABLISHMENT REFORMATIONISTS REMOBILISATIONS
REMONETISATIONS REMORALISATIONS REMOVABLENESSES RESTORATIONISMS
RESYSTEMATISING RESYSTEMATIZING RETINOBLASTOMAS RETRANSMISSIONS
RHEUMATOLOGISTS RUDIMENTARINESS SABERMETRICIANS SACCHARIMETRIES
SACCHAROMETRIES SACCHAROMYCETES SACRAMENTALISMS SACRAMENTALISTS
SACRAMENTALNESS SACRAMENTARIANS SARCENCHYMATOUS SCAREMONGERINGS
SCHOOLMASTERING SCHOOLMASTERISH SCLERODERMATOUS SCRIMSHANDERING
SEISMOGRAPHICAL SEMIABSTRACTION SEMICRYSTALLINE SEMIPARASITISMS
SEMITERRESTRIAL SEMITRANSLUCENT SEMITRANSPARENT SERVOMECHANISMS
SHOCKUMENTARIES SPERMATOBLASTIC SPERMATOGENESES SPERMATOGENESIS
SPERMATORRHOEAS SPHYGMOGRAPHIES STALAGMOMETRIES STRABISMOMETERS
STREPHOSYMBOLIA SUBLAPSARIANISM SUBMETACENTRICS SUBMINIATURISED
SUBMINIATURISES SUBMINIATURIZES SUPERHUMANISING SUPERHUMANITIES
SUPERMAJORITIES SUPERNATURALISM SUPERNUMERARIES SUPERORGANICISM
SUPERPARASITISM SUPERPATRIOTISM SUPERSTIMULATED SUPERSTIMULATES
SUPPLEMENTARIES SYMBOLOGRAPHIES SYMMETRICALNESS SYMMETRISATIONS
SYMMETRIZATIONS SYMMETROPHOBIAS TARSOMETATARSAL TARSOMETATARSUS
TELEJOURNALISMS TELOMERISATIONS TEMERARIOUSNESS TEMPERATENESSES
TEMPORARINESSES TERRITORIALISMS TETARTOHEDRISMS THERMAESTHESIAS
THERMALISATIONS THROMBOPLASTINS TOASTMISTRESSES TRADITIONALISMS
TRANSAMINATIONS TRANSFORMATIONS TRANSGENDERISMS TRANSMIGRATIONS
TRANSMISSOMETER TRANSMITTANCIES TRANSSEXUALISMS TRANSVESTITISMS
TRAUMATISATIONS TRAUMATONASTIES TRIPERSONALISMS TRYPANOSOMIASES
TRYPANOSOMIASIS ULTRAMODERNISMS ULTRAMODERNISTS ULTRAMONTANISMS
ULTRAMONTANISTS UNDEREMPHASISED UNDEREMPHASISES UNDEREMPHASIZES
UNDERSTATEMENTS UNSECTARIANISMS UNSPORTSMANLIKE UNTRANSMISSIBLE
UTILITARIANISMS VISCOSIMETRICAL WARMHEARTEDNESS WEARISOMENESSES