| nclMichoacán Nahuatl | ncl | Uto-Aztecan | | | 6b · Threatened |
| dntMid Grand Valley Dani | dnt | Trans–New Guinea | | | 5 · Developing |
| axmMiddle Armenian | axm | Indo-European | | | |
| cnxMiddle Cornish | cnx | Indo-European | | | |
| dumMiddle Dutch | dum | Indo-European | | | |
| enmMiddle English | enm | Indo-European | | | |
| frmMiddle French | frm | Indo-European | | | |
| gmhMiddle High German | gmh | Indo-European | | | |
| mgaMiddle IrishGaoidhealg | mga | Indo-European | | | |
| okmMiddle Korean중세 한국어 | okm | Koreanic | | | |
| gmlMiddle Low German | gml | Indo-European | | | |
| xngMiddle Mongolian | xng | Mongolic | | | |
| palMiddle Persian | pal | Indo-European | | | |
| mplMiddle Watut | mpl | Austronesian | | | 6a · Vigorous |
| meiMidob | mei | Nilo-Saharan | | | 6a · Vigorous |
| mmyMigaama | mmy | Afroasiatic | | | 5 · Developing |
| sjlMiji | sjl | Sino-Tibetan | | | 6a · Vigorous |
| mxjMiju | mxj | Sino-Tibetan | | | 6a · Vigorous |
| mikMikasuki | mik | Muskogean | | 190 | 6b · Threatened |
| mljMiltu | mlj | Afroasiatic | | | 8a · Moribund |
| czoMin Zhong | czo | Sino-Tibetan | | | 6a · Vigorous |
| zgmMin Zhuang | zgm | Kra–Dai | | | 6a · Vigorous |
| minMinangkabaubahaso Minangkabau | min | — | | 5.5 m | 5 · Developing |
| drcMinderico | drc | Indo-European | | | 8a · Moribund |
| mpnMindiri | mpn | Austronesian | | | 7 · Shifting |
| xrgMineng | xrg | Australian Aboriginal languages | | | 10 · Extinct |
| mkoMingang Doso | mko | Niger–Congo | | | 6b · Threatened |
| lmjMingarbahasa Lembata Barat | lmj | — | | | 6a · Vigorous |
| xmfMingrelianმარგალური ნინა | xmf | — | | 345,530 | 6a · Vigorous |
| htoMinica HuitotoWitoto mɨnɨca | hto | Bora–Witoto | | 1,705 | 7 · Shifting |
| wiiMinidien | wii | Torricelli | | | 8a · Moribund |
| omnMinoan | omn | — | | | |
| mqqMinokok | mqq | Austronesian | | | 6b · Threatened |
| mnqMinriq | mnq | Austroasiatic | | | 6b · Threatened |
| mztMintil | mzt | Austroasiatic | | | 8a · Moribund |
| mykMinyanka | myk | Niger–Congo | | | 4 · Educational |
| mwlMirandeseMirandés | mwl | Indo-European | | 15,000 | 2 · Provincial |
| mmvMiriti | mmv | Tucanoan | | | 9 · Dormant |
| mepMiriwoong | mep | Jarrakan | | 156 | 8b · Nearly Extinct |
| rsmMiriwoong Sign Language | rsm | Jarrakan | | | 8b · Nearly Extinct |
| gmrMirning | gmr | Australian Aboriginal languages | | 4 | |
| pmuMirpuriਮੀਰਪੁਰੀ | pmu | — | | | |
| tlcMisantla Totonac | tlc | Totonacan | | | 8a · Moribund |
| mrgMishing | mrg | Sino-Tibetan | | | 5 · Developing |
| mpxMisima | mpx | — | | | 5 · Developing |
| miqMiskito | miq | Misumalpan | | 180,000 | 6b · Threatened |
| vmmMitlatongo-Yutanduchi Mixtec | vmm | Central American Indian languages | | 2,800 | 6a · Vigorous |
| mwuMittu | mwu | Nilo-Saharan | | | 10 · Extinct |
| zmqMituku | zmq | — | | | 6a · Vigorous |
| mpoMiu | mpo | Austronesian | | | 7 · Shifting |
| vmiMiwa | vmi | Worrorran | | | 10 · Extinct |
| gacMixed Great Andamanese | gac | Andamanese | | | 9 · Dormant |
| zpmMixtepec Zapotec | zpm | Central American Indian languages | | | 5 · Developing |
| mkfMiya | mkf | Afroasiatic | | 30,000 | 6a · Vigorous |
| mviMiyako | mvi | Japonic | | | 8a · Moribund |
| ehsMiyakubo Sign Language宮窪手話 | ehs | — | | 70 | |
| lusMizomizo | lus | Sino-Tibetan | | 500,000 | 4 · Educational |
| mraMlabri | mra | Austroasiatic | | | 6a · Vigorous |
| lhsMlahsô | lhs | Afroasiatic | | | 10 · Extinct |
| kjaMlapbahasa Mlap | kja | Northwest Papuan | | | 8b · Nearly Extinct |
| mloMlomp | mlo | Niger–Congo | | | 6b · Threatened |
| mmuMmaala | mmu | Niger–Congo | | | 6b · Threatened |
| bfmMmen | bfm | — | | | 6a · Vigorous |
| gbnMo'da | gbn | Nilo-Saharan | | | 7 · Shifting |
| obmMoabite | obm | Afroasiatic | | | |
| modMobilian Jargon | mod | — | | | |
| ahmMobu | ahm | Niger–Congo | | | 6b · Threatened |
| mhnMòcheno | mhn | Indo-European | | 1,900 | 6a · Vigorous |
| oldMochi | old | Niger–Congo | | | 6a · Vigorous |
| omcMochica | omc | — | | | Extinct |
| mhcMocho’Qatoʼk | mhc | Central American Indian languages | | | 8a · Moribund |
| mocMocoví | moc | Guaicuruan | | 3,000 | 6b · Threatened |
| mxdModangbahasa Modang | mxd | — | | | 6a · Vigorous |
| ellModern Greekελληνικά | ell | Indo-European | | 15 m | 1 · National |
| hebModern Hebrew | heb | Afroasiatic | | | |
| mqoModole | mqo | West Papuan | | | 6b · Threatened |
| mvqMoere | mvq | Trans–New Guinea | | | 7 · Shifting |
| mifMofu-Gudur | mif | Afroasiatic | | | 5 · Developing |
| mhjMoghol | mhj | Mongolic | | 200 | 9 · Dormant |
| movMohave | mov | Hoka-Sioux | | | 8a · Moribund |
| mohMohawk | moh | Iroquoian | | 3,500 | 6b · Threatened |
| xpqMohegan-Pequot | xpq | Algic | | | 9 · Dormant |
| mxnMoibahasa Moi | mxn | West Papuan | | | 6b · Threatened |
| mwzMoingi | mwz | Niger–Congo | | | 6b · Threatened |
| ymiMoji | ymi | Sino-Tibetan | | | 7 · Shifting |
| mqtMok | mqt | Austroasiatic | | | 6a · Vigorous |
| mwtMoken | mwt | Austronesian | | | 6b · Threatened |
| mftMokerang | mft | Austronesian | | | 6a · Vigorous |
| mkjMokileselal in Mwoakilloa | mkj | Austronesian | | | 6a · Vigorous |
| mozMokilko | moz | Afroasiatic | | | 5 · Developing |
| mkmMoklen | mkm | Austronesian | | | 6b · Threatened |
| mklMokole | mkl | Niger–Congo | | 39,600 | 5 · Developing |
| vmsMoksela | vms | — | | | 10 · Extinct |
| mdfMokshaМокшень кяль | mdf | Uralic | | 2,025 | 6b · Threatened |
| alxMol | alx | Torricelli | | | 7 · Shifting |
| mbeMolala | mbe | — | | | 10 · Extinct |
| pwmMolbog | pwm | Austronesian | | | 5 · Developing |
| vsiMoldova Sign Language | vsi | — | | | 5 · Developing |
| molMoldovanLimba moldovenească | mol | Indo-European | | 2 m | |
| moxMolima | mox | Austronesian | | | 5 · Developing |
| aunMolmo One | aun | Torricelli | | | 6b · Threatened |
| zmoMolo | zmo | Nilo-Saharan | | | 8b · Nearly Extinct |
| mslMolofbahasa Ampas | msl | — | | | 6b · Threatened |
| mlwMoloko | mlw | Afroasiatic | | 8,500 | 5 · Developing |
| mylMoma | myl | Austronesian | | | 5 · Developing |
| mszMomare | msz | Trans–New Guinea | | | 8b · Nearly Extinct |
| msoMombum | mso | Trans–New Guinea | | | 8a · Moribund |
| mmbMominabahasa Momina | mmb | — | | | 6b · Threatened |
| mqfMomunabahasa Momuna | mqf | — | | | 6b · Threatened |
| mnwMonဘာသာမန် | mnw | Austroasiatic | | 850,000 | 5 · Developing |
| mndMondé | mnd | Tupian | | | 9 · Dormant |
| npnMondropolon | npn | Austronesian | | | 6a · Vigorous |
| lolMongo | lol | Niger–Congo | | | 5 · Developing |
| mgtMongol | mgt | Mongol–Langam | | | 6b · Threatened |
| bxmMongolia Buriat | bxm | Mongolic | | 42,500 | 6a · Vigorous |
| monMongolianмонгол хэл | mon | Mongolic | | 7 m | |
| msrMongolian Sign Language | msr | — | | | 6a · Vigorous |
| mogMongondow | mog | Austronesian | | | 7 · Shifting |
| njoMongsen Ao | njo | Sino-Tibetan | | 261,000 | 4 · Educational |
| mjgMonguor | mjg | Mongolic | | 152,000 | 7 · Shifting |
| mnzMoniMilano | mnz | Trans–New Guinea | | 20,000 | 5 · Developing |
| mhmMoniga | mhm | Niger–Congo | | | 6a · Vigorous |
| mruMono | mru | Niger–Congo | | | 8a · Moribund |
| mnhMono | mnh | Niger–Congo | | | 6a · Vigorous |
| mteMono | mte | Austronesian | | 2,940 | 6a · Vigorous |
| mnrMono | mnr | Uto-Aztecan | | | 8a · Moribund |
| cnrMontenegrincrnogorski jezik | cnr | Indo-European | | 232,600 | 1 · National |
| mxkMonumbo | mxk | Torricelli | | | 6b · Threatened |
| gwgMoo | gwg | — | | 5,000 | 6a · Vigorous |
| mosMoorémòoré | mos | Niger–Congo | +1 | 7.6 m | 3 · Wider Communication |
| crmMoose Cree | crm | — | | | 6b · Threatened |
| mopMopan Maya | mop | Central American Indian languages | | | 5 · Developing |
| moqMor | moq | — | | | 8a · Moribund |
| mhzMor | mhz | Austronesian | | | 7 · Shifting |
| msgMoraidbahasa Moraid | msg | West Papuan | | | 6b · Threatened |
| mzeMorawa | mze | Trans–New Guinea | | | 6a · Vigorous |
| nhmMorelos Nahuatl | nhm | Uto-Aztecan | | | 6a · Vigorous |
| msxMoresada | msx | Trans–New Guinea | | | 6b · Threatened |
| mzqMori Atasbahasa Mori Atas | mzq | Austronesian | | | 6b · Threatened |
| xmzMori Bawahbahasa Mori Bawah | xmz | Austronesian | | | 6b · Threatened |
| mdbMorigi | mdb | Kiwaian | | | 6a · Vigorous |
| rrmMoriori | rrm | Austronesian | | | |
| morMoro | mor | Niger–Congo | | | 5 · Developing |
| aryMoroccan Arabicالداريجة | ary | Afroasiatic | | 27.5 m | 3 · Wider Communication |
| mgcMorokodo | mgc | Nilo-Saharan | | | 6a · Vigorous |
| bdoMorom | bdo | Nilo-Saharan | | | 6a · Vigorous |
| mqnMoronene | mqn | Austronesian | | | 6a · Vigorous |
| mokMororibahasa Morori | mok | — | | 50 | 8a · Moribund |
| mrpMorouas | mrp | Austronesian | | | 6b · Threatened |
| mrlMortlockesekapasen Mwoshulók | mrl | Austronesian | | | 6b · Threatened |
| mgdMoru | mgd | Nilo-Saharan | | | 4 · Educational |
| mqvMosimo | mqv | Trans–New Guinea | | | 7 · Shifting |
| bzkMoskitian Creole | bzk | — | | | 4 · Educational |
| mtjMoskona | mtj | — | | | 5 · Developing |
| mttMota | mtt | Austronesian | | | 6b · Threatened |
| meuMotu | meu | Austronesian | | 39,000 | 5 · Developing |
| mwhMouk-Aria | mwh | Austronesian | | | 5 · Developing |
| atlMount Iraya Agta | atl | Austronesian | | | 6b · Threatened |
| agzMount Iriga Agta | agz | Austronesian | | | 6b · Threatened |
| kpxMountain Koiali | kpx | Trans–New Guinea | | | 5 · Developing |
| jmwMouwase | jmw | — | | 450 | 6a · Vigorous |
| mzpMovima | mzp | — | | | 8a · Moribund |
| ityMoyadan Itneg | ity | Austronesian | | | 6a · Vigorous |
| mowMoye | mow | Niger–Congo | | | 6b · Threatened |
| nmoMoyon | nmo | Sino-Tibetan | | | 5 · Developing |
| mzbMozabite | mzb | Afroasiatic | | 150,000 | 6b · Threatened |
| xnqMozambican Ngoni | xnq | Niger–Congo | | | |
| mzyMozambican Sign Language | mzy | — | | | 5 · Developing |
| mxiMozarabic | mxi | Indo-European | | | |
| mpiMpade | mpi | Afroasiatic | | | 6b · Threatened |
| xpjMpalitjanh | xpj | Australian Aboriginal languages | | | 10 · Extinct |
| mpzMpi | mpz | Sino-Tibetan | | | 6b · Threatened |
| mcxMpiemo | mcx | Niger–Congo | | | 6a · Vigorous |
| pndMpinda | pnd | Niger–Congo | | | 6b · Threatened |
| mpaMpoto | mpa | Niger–Congo | | | 6a · Vigorous |
| mvtMpotovoro | mvt | Austronesian | | | 6b · Threatened |
| mggMpumpong | mgg | Niger–Congo | | | 6a · Vigorous |
| cmrMro-Khimi | cmr | Sino-Tibetan | | | 6b · Threatened |
| mroMru | mro | Sino-Tibetan | | | 5 · Developing |
| kqxMser | kqx | Afroasiatic | | | 8a · Moribund |
| ukkMuak Sa-aak | ukk | Austroasiatic | | 4,500 | 5 · Developing |
| mtdMualang | mtd | Austronesian | | | 5 · Developing |
| mubMubi | mub | Afroasiatic | | | 6a · Vigorous |
| ymdMuda | ymd | Sino-Tibetan | | | 6b · Threatened |
| dmwMudbura | dmw | Australian Aboriginal languages | | 92 | 8b · Nearly Extinct |
| udgMuduga | udg | Dravidian | | | 6a · Vigorous |
| aojMufian | aoj | Torricelli | | | 5 · Developing |
| mukMugom | muk | Sino-Tibetan | | | 6a · Vigorous |
| bmrMuinaneMuìnánɨ | bmr | Bora–Witoto | | 150 | 7 · Shifting |
| mmkMukha-Dora | mmk | Dravidian | | | 6a · Vigorous |
| vmoMukomuko | vmo | — | | | |
| mfwMulaha | mfw | — | | | 10 · Extinct |
| mlmMulam | mlm | Kra–Dai | | 86,000 | 6b · Threatened |
| giuMulao | giu | Kra–Dai | | | 8b · Nearly Extinct |
| kpbMullu Kurumba | kpb | Dravidian | | | 6a · Vigorous |
| mzmMumuye | mzm | Niger–Congo | | | 5 · Developing |
| mnbMuna | mnb | Austronesian | | 300,000 | 6b · Threatened |
| boeMundabli | boe | Niger–Congo | | | 6b · Threatened |
| muaMundang | mua | Niger–Congo | | | 5 · Developing |
| mnfMundani | mnf | — | | | 5 · Developing |
| unrMundari | unr | Austroasiatic | | 1.5 m | 5 · Developing |
| mmfMundat | mmf | Afroasiatic | | | 6b · Threatened |
| muhMündü | muh | — | | | 5 · Developing |
| myuMunduruku | myu | Tupian | | 7,000 | 6a · Vigorous |
| mijMungbam | mij | Niger–Congo | | | 6b · Threatened |
| mthMungguibahasa Munggui | mth | Austronesian | | | 6b · Threatened |
| mpvMungkip | mpv | Trans–New Guinea | | | 8b · Nearly Extinct |
| myrMunichi | myr | — | | | 9 · Dormant |
| mtcMunit | mtc | Trans–New Guinea | | | 6a · Vigorous |
| mnjMunji | mnj | Indo-European | | 3,770 | 6a · Vigorous |
| bvmMunka | bvm | — | | | 5 · Developing |
| umuMunseehulŭniixsuwáakan | umu | Algic | | | 8b · Nearly Extinct |
| mtqMuong | mtq | Austroasiatic | | 1.1 m | 6a · Vigorous |
| tkvMur Pano | tkv | Austronesian | | | 6a · Vigorous |
| asxMuratayak | asx | Trans–New Guinea | | | 6a · Vigorous |
| mxrMurik Kayan | mxr | Austronesian | | | 7 · Shifting |
| rmhMurkimbahasa Murkim | rmh | — | | 290 | 6a · Vigorous |
| murMurle | mur | Nilo-Saharan | | | 5 · Developing |
| mwfMurrinh-patha | mwf | Daly | | | 5 · Developing |
| muzMursi | muz | Nilo-Saharan | | 7,500 | 5 · Developing |
| huuMurui Huitoto | huu | Bora–Witoto | | 2,900 | 6b · Threatened |
| zmuMuruwari | zmu | Australian Aboriginal languages | | | 9 · Dormant |
| mmqMusak | mmq | Trans–New Guinea | | 400 | 6b · Threatened |
| mmiMusar | mmi | — | | | 6a · Vigorous |
| smmMusasa | smm | Indo-European | | | 6b · Threatened |
| musMuscogeeMvskoke | mus | Muskogean | | 4,300 | 7 · Shifting |
| mseMusey | mse | Afroasiatic | | | 5 · Developing |
| mugMusgu | mug | Afroasiatic | | | 5 · Developing |
| xmaMushungulu | xma | Niger–Congo | | 23,000 | 6b · Threatened |
| muiMusiBasé Musi | mui | Austronesian | | | 3 · Wider Communication |
| tttMuslim Tat | ttt | Indo-European | | | |
| msuMusom | msu | Austronesian | | | 7 · Shifting |
| emiMussau-Emira | emi | Austronesian | | | 5 · Developing |
| muvMuthuvan | muv | Dravidian | | | 6a · Vigorous |
| tucMutu | tuc | Austronesian | | | 4 · Educational |
| mvmMuya | mvm | Sino-Tibetan | | | 6b · Threatened |
| muyMuyang | muy | Afroasiatic | | | 5 · Developing |
| mywMuyuw | myw | Austronesian | | | 5 · Developing |
| ymzMuzi | ymz | Sino-Tibetan | | | 7 · Shifting |
| mcjMvanip | mcj | Niger–Congo | | | 6a · Vigorous |
| mxhMvuba | mxh | Nilo-Saharan | | | 6b · Threatened |
| surMwaghavul | sur | Afroasiatic | | | 3 · Wider Communication |
| wlcMwali Comorian | wlc | Niger–Congo | | 28,700 | 6a · Vigorous |
| moaMwan | moa | Niger–Congo | | | 5 · Developing |
| mwnMwanga | mwn | Niger–Congo | | | 5 · Developing |
| wmwMwaniKimwani | wmw | Niger–Congo | | 100,000 | 5 · Developing |
| mwaMwatebu | mwa | Austronesian | | | 6b · Threatened |
| mweMwera | mwe | Niger–Congo | | | 6a · Vigorous |
| mrmMwerlap | mrm | Austronesian | | | 6a · Vigorous |
| msnMwesen | msn | Austronesian | | | Critically endangered |
| mwsMwimbi-Muthambi | mws | Niger–Congo | | | 6a · Vigorous |
| mlvMwotlap | mlv | Austronesian | | | 6a · Vigorous |
| gmyMycenaean GreekΜυκηναϊκή ελληνική | gmy | Indo-European | | | |
| myeMyene | mye | Niger–Congo | | | 6a · Vigorous |
| nmeMzieme | nme | Sino-Tibetan | | | 5 · Developing |