| kswS'gaw Karen | ksw | Sino-Tibetan | | 4 m | 3 · Wider Communication |
| apbSa'a | apb | Austronesian | | | 5 · Developing |
| snvSa'ban | snv | Austronesian | | | 6b · Threatened |
| scqSa'och | scq | Austroasiatic | | 10 | 8b · Nearly Extinct |
| saxSaa | sax | Austronesian | | | 6a · Vigorous |
| raqSaam | raq | Sino-Tibetan | | | 8a · Moribund |
| lsmsaamia | lsm | Niger–Congo | | | 5 · Developing |
| asjSaari | asj | Niger–Congo | | | 5 · Developing |
| sxrSaaroa | sxr | Austronesian | | 10 | 8b · Nearly Extinct |
| saaSaba | saa | Afroasiatic | | | 6b · Threatened |
| xsaSabaean | xsa | Afroasiatic | | | |
| bsySabah Bisaya | bsy | Austronesian | | | 6b · Threatened |
| msiSabah Malay | msi | Austronesian | | 3 m | 3 · Wider Communication |
| saeSabanês | sae | Nambikwaran | | 3 | 8b · Nearly Extinct |
| spySabaot | spy | Nilo-Saharan | | | 5 · Developing |
| sbvSabine | sbv | Indo-European | | | |
| kpzSabiny | kpz | Nilo-Saharan | | | 5 · Developing |
| pmlSabir | pml | Indo-European | | | 10 · Extinct |
| sboSabüm | sbo | Austroasiatic | | | 9 · Dormant |
| sacSac-Fox-Kickapoo | sac | Algic | | 250 | 8a · Moribund |
| skbSaek | skb | — | | | 7 · Shifting |
| safSafaliba | saf | Niger–Congo | | 9,000 | 5 · Developing |
| savSafen | sav | Niger–Congo | | | 5 · Developing |
| apzSafeyoka | apz | — | | 2,390 | 5 · Developing |
| sbkSafwa | sbk | Niger–Congo | | | 6a · Vigorous |
| sbmSagara | sbm | Niger–Congo | | 79,000 | 6b · Threatened |
| ssySaho | ssy | Afroasiatic | | 271,180 | 5 · Developing |
| sajSahu | saj | West Papuan | | 3,500 | 5 · Developing |
| aecSaʽidi Arabicصعيدي | aec | Afroasiatic | | 22.4 m | 6a · Vigorous |
| acfSaint Lucian Creole Frenchkweyol | acf | Antillean Creole | | | 5 · Developing |
| xsySaisiyat | xsy | Austronesian | | 4,750 | 6b · Threatened |
| ckhSak | ckh | Sino-Tibetan | | 4,000 | 6a · Vigorous |
| skgSakalava Malagasy | skg | Austronesian | | | 6a · Vigorous |
| skuSakao | sku | Austronesian | | | 6a · Vigorous |
| quvSakapultek | quv | Central American Indian languages | | | 7 · Shifting |
| sktSakata | skt | Niger–Congo | | | 6a · Vigorous |
| sakSake | sak | Niger–Congo | | | 8a · Moribund |
| skfSakirabiá | skf | Tupian | | | 8a · Moribund |
| szySakizaya | szy | Austronesian | | 958 | 4 · Educational |
| slxSalampasu | slx | Niger–Congo | | | 6a · Vigorous |
| slrSalarSalïrča | slr | Turkic | | 70,000 | 6b · Threatened |
| sguSalas | sgu | Austronesian | | 50 | 8b · Nearly Extinct |
| qxlSalasaca Highland Quichua | qxl | Quechua | | | 6a · Vigorous |
| xmxSalawatibahasa Saparan | xmx | — | | | 6b · Threatened |
| sauSaleman | sau | Austronesian | | 4,800 | 6b · Threatened |
| slcSaliba | slc | Piaroa–Saliban | | 1,500 | 8a · Moribund |
| sbeSaliba | sbe | Austronesian | | | 5 · Developing |
| slnSalinan | sln | — | | | 9 · Dormant |
| flaSalish-Spokane-Kalispel | fla | — | | | 8b · Nearly Extinct |
| sdzSallaans | sdz | Indo-European | | | 6a · Vigorous |
| loeSaluanbahasa Loinang | loe | Austronesian | | | 6b · Threatened |
| esnSalvadoran Sign Language | esn | — | | | 4 · Educational |
| smdSama | smd | Niger–Congo | | | 6a · Vigorous |
| samSamaritan Aramaic | sam | — | | | 9 · Second language only |
| smpSamaritan Hebrewעברית שומרונית | smp | Afroasiatic | | | 9 · Second language only |
| tmjSamarokenabahasa Samarkena | tmj | Tor-Kwerba | | | 6b · Threatened |
| ysdSamatao | ysd | Sino-Tibetan | | | 8a · Moribund |
| syxSamay | syx | Niger–Congo | | | 6b · Threatened |
| smxSamba | smx | Niger–Congo | | | 6b · Threatened |
| xsbSambal | xsb | Austronesian | | 70,000 | 7 · Shifting |
| spvSambalpuri | spv | Indo-European | | 2.6 m | 4 · Educational |
| xabSambe | xab | Niger–Congo | | | 8b · Nearly Extinct |
| saqSamburu | saq | — | | | 6a · Vigorous |
| smhSamei | smh | Sino-Tibetan | | | 6b · Threatened |
| smqSamo | smq | — | | | 5 · Developing |
| smoSamoanGagana fa'a Sāmoa | smo | Austronesian | +2 | 415,720 | 1 · National |
| sgsSamogitianŽemaitiu ruoda | sgs | Indo-European | | 500,000 | 5 · Developing |
| swmSamosa | swm | Trans–New Guinea | | | 7 · Shifting |
| ravSampang | rav | Sino-Tibetan | | | 6b · Threatened |
| sxmSamre | sxm | Austroasiatic | | | 9 · Dormant |
| stuSamtao | stu | — | | | 6a · Vigorous |
| wbfSamwe | wbf | Niger–Congo | | | 6a · Vigorous |
| ztmSan Agustín Mixtepec Zapotec | ztm | Central American Indian languages | | | 8b · Nearly Extinct |
| icrSan Andrés–Providencia Creole | icr | — | | | 6a · Vigorous |
| zpbSan Bartolo Yautepec Zapotec | zpb | Central American Indian languages | | | 7 · Shifting |
| hveSan Dionisio del Mar Huave | hve | — | | | 7 · Shifting |
| hueSan Francisco del Mar Huave | hue | — | | | 7 · Shifting |
| huvSan Mateo Del Mar Huave | huv | — | | | 5 · Developing |
| scfSan Miguel Creole French | scf | Antillean Creole | | | 10 · Extinct |
| azgSan Pedro Amuzgos Amuzgo | azg | Central American Indian languages | | | 6a · Vigorous |
| aynSanʽani Arabic | ayn | Afroasiatic | | 11.4 m | 6a · Vigorous |
| sapSanapaná | sap | Mascoian | | | 6b · Threatened |
| sadSandawe | sad | Khoisan | | 40,000 | 6a · Vigorous |
| sngSanga | sng | Niger–Congo | | | 5 · Developing |
| xsnSanga | xsn | Niger–Congo | | | 6a · Vigorous |
| scgSanggaubahasa Sanggau | scg | Austronesian | | | 6a · Vigorous |
| snlSangil | snl | Austronesian | | | 5 · Developing |
| sxnSangirese | sxn | Austronesian | | | 5 · Developing |
| sgkSangkong | sgk | Sino-Tibetan | | | 6b · Threatened |
| sgySanglechisangleči zǝvūk | sgy | Indo-European | | | 6a · Vigorous |
| sagSangoSängö | sag | Niger–Congo | | 500,000 | 1 · National |
| sgrSangsari | sgr | Indo-European | | | 6a · Vigorous |
| nsaSangtam | nsa | — | | | 4 · Educational |
| snqSangu | snq | Niger–Congo | | | 6a · Vigorous |
| sbpSangu | sbp | Niger–Congo | | | 6b · Threatened |
| ysySanie | ysy | Sino-Tibetan | | | 8a · Moribund |
| snySanio | sny | Sepik | | 1,300 | 5 · Developing |
| mscSankaran Maninka | msc | Niger–Congo | | | 6a · Vigorous |
| ssiSansi | ssi | Indo-European | | | 7 · Shifting |
| sanSanskritसंस्कृतम् | san | Indo-European | | 14,135 | 4 · Educational |
| sceSanta | sce | Mongolic | | 200,000 | 6b · Threatened |
| hvvSanta Maria Del Mar Huave | hvv | — | | | 7 · Shifting |
| nhzSanta María La Alta Nahuatl | nhz | Uto-Aztecan | | | 7 · Shifting |
| satSantali | sat | Austroasiatic | +1 | 7.2 m | 4 · Educational |
| qusSantiagueño QuechuaArhintinap runasimin | qus | Quechua | | 170,000 | 6a · Vigorous |
| zpsSanto Domingo Coatlán Zapotec | zps | Central American Indian languages | | | 7 · Shifting |
| snwSantrokofi | snw | Niger–Congo | | | 5 · Developing |
| xsuSanumáSanöma | xsu | Yanomaman | | | 5 · Developing |
| sprSaparuabahasa Saparua | spr | Austronesian | | | 8a · Moribund |
| spcSapé | spc | — | | | 9 · Dormant |
| spiSaponibahasa Saponi | spi | Lakes Plain | | | 10 · Extinct |
| spsSaposa | sps | Austronesian | | | 5 · Developing |
| mwmSar | mwm | Nilo-Saharan | | | 3 · Wider Communication |
| sreSara Bakati'bahasa Bakati’ Sara | sre | Austronesian | | | 6a · Vigorous |
| skrSaraikiسرائیکی | skr | — | +1 | 20 m | 4 · Educational |
| srmSaramaccanSaamáka | srm | Dutch-based creole languages | | 90,000 | 5 · Developing |
| bpsSarangani Blaan | bps | Austronesian | | | 5 · Developing |
| zsaSarasira | zsa | Austronesian | | 600 | 6b · Threatened |
| sarSaraveca | sar | Paresi–Waura | | | 10 · Extinct |
| srdSardiniansardu | srd | Indo-European | +2 | 1.3 m | Definitely endangered |
| srhSarikoli | srh | — | | 16,000 | 6b · Threatened |
| sdfSarli | sdf | Indo-European | | | 7 · Shifting |
| swySarua | swy | Afroasiatic | | | 7 · Shifting |
| sduSarudu | sdu | — | | | 6b · Threatened |
| sraSaruga | sra | Trans–New Guinea | | | 6b · Threatened |
| sasSasakᬪᬵᬲᬵᬲᬓ᭄ᬱᬓ᭄ | sas | Austronesian | | 2 m | 5 · Developing |
| sdcSassareseSassaresu | sdc | Indo-European | | 100,000 | 6b · Threatened |
| stwSatawalesekepesaen Saetaewan | stw | Austronesian | | | 5 · Developing |
| stqSaterland FrisianSeeltersk | stq | Indo-European | | 1,000 | 7 · Shifting |
| sdlSaudi Sign Language | sdl | — | | | 6a · Vigorous |
| sazSaurashtra | saz | Indo-European | | 300,000 | 5 · Developing |
| srtSauribahasa Sauri | srt | Geelvink Bay | | | 6b · Threatened |
| mjtSauria Paharia | mjt | Dravidian | | | 5 · Developing |
| saoSausebahasa Sause | sao | — | | | 6b · Threatened |
| sdgSavi | sdg | — | | | 6a · Vigorous |
| svsSavosavo | svs | — | | | 6a · Vigorous |
| szwSawai | szw | Austronesian | | 12,000 | 6b · Threatened |
| swrSawerubahasa Saweru | swr | — | | | 6b · Threatened |
| sawSawibahasa Aejauroh | saw | — | | | 8a · Moribund |
| swtSawilabahasa Sawila | swt | Trans–New Guinea | | | 6b · Threatened |
| sxwSaxwe | sxw | Niger–Congo | | | 5 · Developing |
| saySaya | say | Afroasiatic | | 300,000 | 6a · Vigorous |
| posSayula Popoluca | pos | Mixe–Zoque | | | 6b · Threatened |
| scoScotsScots leid | sco | Indo-European | | 1.6 m | 5 · Developing |
| trlScottish Cant | trl | Indo-European | | | 6b · Threatened |
| glaScottish GaelicGàidhlig na h-Alba | gla | Indo-European | +2 | 57,000 | 2 · Provincial |
| kdgSeba | kdg | Austronesian | | | 6b · Threatened |
| sgwSebat Bet Gurage | sgw | Afroasiatic | | 1.5 m | 5 · Developing |
| snbSebuyau | snb | Austronesian | | | 6b · Threatened |
| secSechelt | sec | Salishan | | | 8b · Nearly Extinct |
| seySecoyaPaikoka | sey | Tucanoan | | 1,200 | 7 · Shifting |
| sedSedang | sed | Austroasiatic | | | 6a · Vigorous |
| trvSeediqKari Seediq | trv | Austronesian | | 20,000 | 4 · Educational |
| sgeSegai | sge | Austronesian | | | 6b · Threatened |
| segSegeju | seg | Niger–Congo | | | 8a · Moribund |
| sbgSeget | sbg | West Papuan | | | 6b · Threatened |
| sfwSehwi | sfw | Niger–Congo | | | 5 · Developing |
| simSeim | sim | Sepik | | | 4 · Educational |
| ssgSeimat | ssg | Austronesian | | | 4 · Educational |
| hikSeit-Kaitetu | hik | — | | | 6b · Threatened |
| sekSekani | sek | Na-Dene | | | 8a · Moribund |
| skzSekar | skz | Austronesian | | | 6b · Threatened |
| skjSeke | skj | Bodish | | | 6a · Vigorous |
| vajSekele | vaj | Khoisan | | 5,600 | 6a · Vigorous |
| syiSeki | syi | Niger–Congo | | | 6b · Threatened |
| skxSeko Pandangbahasa Seko Padang | skx | — | | | 6a · Vigorous |
| skoSeko Tengahbahasa Pohoneang | sko | — | | | 6b · Threatened |
| sluSelaru | slu | Austronesian | | 1,823 | 6b · Threatened |
| slySelayar | sly | — | | | 6a · Vigorous |
| selSelkup | sel | Uralic | | 600 | 5 · Developing |
| sxlSelonian | sxl | Indo-European | | | Extinct |
| stvSeltiየስልጤ | stv | Afroasiatic | | 935,000 | 4 · Educational |
| swsSeluwasanbahasa Seluwasan | sws | Austronesian | | 2,839 | 6b · Threatened |
| seaSemai | sea | Austroasiatic | | 10,000 | 3 · Wider Communication |
| sdqSemandangbahasa Kualan-Semandang | sdq | Austronesian | | | 6a · Vigorous |
| szcSemaq Beri | szc | Austroasiatic | | | 6a · Vigorous |
| sbrSembakung | sbr | — | | | 6b · Threatened |
| sosSembla | sos | Niger–Congo | | | 6a · Vigorous |
| szaSemelai | sza | Austroasiatic | | | 6b · Threatened |
| sddSemendobahasa Semende | sdd | Austronesian | | | |
| xzmSemigallian | xzm | Indo-European | | | 10 · Extinct |
| etzSemimibahasa Etna Bay | etz | — | | | 7 · Shifting |
| ssmSemnam | ssm | Austroasiatic | | | 6b · Threatened |
| smySemnani | smy | Indo-European | | 68,700 | 6a · Vigorous |
| xseSempanbahasa Sempan | xse | — | | | 6b · Threatened |
| seqSenara | seq | — | | | 6a · Vigorous |
| synSenaya | syn | — | | | 8b · Nearly Extinct |
| sejSene | sej | Trans–New Guinea | | | 10 · Extinct |
| seeSeneca | see | Iroquoian | | 100 | 8a · Moribund |
| sdsSened | sds | Afroasiatic | | | 10 · Extinct |
| spkSengo | spk | Sepik | | | 6a · Vigorous |
| sszSengseng | ssz | Austronesian | | | 6b · Threatened |
| sjsSenhaja de SrairTaṣenhajit | sjs | Afroasiatic | | 86,000 | 6b · Threatened |
| sniSensi | sni | Pano-Tacanan | | | 10 · Extinct |
| setSentani | set | Sentani | | | 5 · Developing |
| stdSentinelese | std | — | | | 6b · Threatened |
| spbSepabahasa Sepa | spb | Austronesian | | | 6b · Threatened |
| speSepa | spe | Austronesian | | | 6b · Threatened |
| iwsSepik Iwam | iws | Sepik | | | 5 · Developing |
| srySera | sry | Austronesian | | | 7 · Shifting |
| srjSerawaibahasa Serawai | srj | Austronesian | | | |
| srpSerbianсрпски језик | srp | — | +3 | 9 m | 1 · National |
| hbsSerbo-Croatiansrpskohrvatski jezik | hbs | Indo-European | +2 | 19 m | |
| swfSere | swf | Niger–Congo | | | 8b · Nearly Extinct |
| srrSererSeereer | srr | Niger–Congo | | 1.2 m | 5 · Developing |
| seiSericmiique iitom | sei | Hoka-Sioux | | 900 | 6b · Threatened |
| sveSerilibahasa Serili | sve | Austronesian | | | 8a · Moribund |
| kquSeroa | kqu | Khoisan | | | 10 · Extinct |
| serSerranoMaarrênga'twich | ser | Uto-Aztecan | | | 9 · Dormant |
| szdSeru | szd | — | | | Extinct |
| srwSeruabahasa Serua | srw | Austronesian | | 1,013 | 10 · Extinct |
| srkSerudung | srk | Austronesian | | | 6b · Threatened |
| seuSerui-Laut | seu | — | | | 7 · Shifting |
| ntdSesayap Tidung | ntd | Austronesian | | | 7 · Shifting |
| sotSesothoseSotho | sot | Niger–Congo | | 6 m | 1 · National |
| stfSeta | stf | Torricelli | | | 6b · Threatened |
| stmSetaman | stm | Trans–New Guinea | | | 6a · Vigorous |
| sbiSeti | sbi | Torricelli | | | 6b · Threatened |
| sewSewa Bay | sew | Austronesian | | | 6a · Vigorous |
| crsSeychellois Creole | crs | French-based creole languages | | 85,000 | 1 · National |
| szeSeze | sze | Mao | | | 7 · Shifting |
| scwSha | scw | Afroasiatic | | 3,000 | 6b · Threatened |
| sdbShabaki | sdb | Indo-European | | | 7 · Shifting |
| sbfShabo | sbf | — | | 400 | 6b · Threatened |
| srzShahmirzadi | srz | Indo-European | | | 6a · Vigorous |
| shmShahrudi | shm | Indo-European | | | 7 · Shifting |
| moyShakacho | moy | Afroasiatic | | | 4 · Educational |
| shaShall-Zwall | sha | Niger–Congo | | | 6a · Vigorous |
| ksbShambala | ksb | Niger–Congo | | 664,000 | 6a · Vigorous |
| shnShanလိၵ်ႈတႆး | shn | Kra–Dai | | 3 m | 3 · Wider Communication |
| swoShanenawa | swo | Pano-Tacanan | | | 8b · Nearly Extinct |
| shoShanga | sho | Niger–Congo | | | 6a · Vigorous |
| mcdSharanahua | mcd | Pano-Tacanan | | | 5 · Developing |
| swqSharwa | swq | Afroasiatic | | | 6a · Vigorous |
| shtShasta | sht | Hoka-Sioux | | | 10 · Extinct |
| shjShatt | shj | Nilo-Saharan | | | 6b · Threatened |
| sqhShau | sqh | Niger–Congo | | | 10 · Extinct |
| shyShawiyaTacawit | shy | Afroasiatic | | 2.3 m | 6a · Vigorous |
| sjwShawneesâwanwâtowêwe | sjw | Algic | | | 8a · Moribund |
| shxShe | shx | Hmong–Mien | | | 7 · Shifting |
| shvShehri | shv | Afroasiatic | | | 6b · Threatened |
| swvShekhawati | swv | Indo-European | | | 5 · Developing |
| sheSheko | she | Dizoid | | | 4 · Educational |
| sthSheltaGammon | sth | Indo-European | | 86,000 | 6a · Vigorous |
| cnuShenwa | cnu | Afroasiatic | | | 7 · Shifting |
| bunSherbro | bun | Niger–Congo | | | 6a · Vigorous |
| sdpSherdukpen | sdp | Sino-Tibetan | | 9,663 | 6a · Vigorous |
| xsrSherpa | xsr | — | | 150,000 | 5 · Developing |
| kipSheshi Kham | kip | Sino-Tibetan | | | 6b · Threatened |
| sczShetlandicShaetlan | scz | Indo-European | | | |
| shrShi | shr | Niger–Congo | | | 5 · Developing |
| sshShihhi Arabic | ssh | Afroasiatic | | | 6a · Vigorous |
| guaShiki | gua | Niger–Congo | | | 8a · Moribund |
| shkShilluk | shk | Nilo-Saharan | | 2 m | 5 · Developing |
| sclShinaݜݨیاٗ | scl | — | | 720,200 | 6a · Vigorous |
| bwoShinasha | bwo | Afroasiatic | | | 4 · Educational |
| asgShingini | asg | Niger–Congo | | | 5 · Developing |
| nyrShinyiha | nyr | Niger–Congo | | | 6b · Threatened |
| shpShipibo-Conibo | shp | Pano-Tacanan | | 34,152 | 5 · Developing |
| xirShiriana | xir | — | | | 9 · Dormant |
| sxgShixing | sxg | Sino-Tibetan | | | 6b · Threatened |
| cshShö | csh | Sino-Tibetan | | | 5 · Developing |
| sleSholaga | sle | Dravidian | | 24,000 | 6a · Vigorous |
| siiShompen | sii | — | | | 6a · Vigorous |
| snaShonaChiShona | sna | Niger–Congo | +1 | 9 m | 3 · Wider Communication |
| bcvShoo-Minda-Nye | bcv | Niger–Congo | | | 6a · Vigorous |
| cjsShor | cjs | Turkic | | 2,839 | 7 · Shifting |
| shhShoshoni | shh | Uto-Aztecan | | 1,000 | 6b · Threatened |
| shgShua | shg | Khoisan | | | 7 · Shifting |
| sdtShuaditJudeoprovençau | sdt | — | | | 10 · Extinct |
| jivShuar | jiv | Jivaroan-Cahuapanan | | 35,000 | 5 · Developing |
| sujShubi | suj | Niger–Congo | | | 6b · Threatened |
| sghShughnixuɣ̌nůni ziv / хуг̌ну̊ни зив | sgh | — | | 64,800 | 6a · Vigorous |
| stsShumashtiݭمݭتی | sts | Indo-European | | | 6a · Vigorous |
| scuShumcho | scu | Bodish | | | 6b · Threatened |
| shsShuswap | shs | Salishan | | | 8a · Moribund |
| ksaShuwa-Zamani | ksa | Niger–Congo | | | 6b · Threatened |
| shwShwai | shw | Niger–Congo | | | 6b · Threatened |
| spgSian | spg | Austronesian | | | 6b · Threatened |
| snpSiane | snp | — | | 29,000 | 5 · Developing |
| syaSiang | sya | Austronesian | | | 6a · Vigorous |
| sjrSiar-Lak | sjr | Austronesian | | | 5 · Developing |
| mmpSiawi | mmp | — | | 220 | 6b · Threatened |
| stySiberian TatarСебертатарца | sty | Turkic | | 101,000 | 6a · Vigorous |
| sdxSibu | sdx | Austronesian | | | 7 · Shifting |
| scnSicilianSicilianu | scn | Indo-European | | 4.7 m | 5 · Developing |
| sqrSiculo-Arabicصقلية عربية | sqr | — | | | |
| sidSidamo | sid | Afroasiatic | | 1.8 m | 4 · Educational |
| xsdSidetic | xsd | Indo-European | | | |
| sgxSierra Leonean Sign Language | sgx | — | | | 6a · Vigorous |
| poiSierra Popoluca | poi | Mixe–Zoque | | 36,000 | 5 · Developing |
| tosSierra Totonac | tos | Totonacan | | | 5 · Developing |
| sxeSighu | sxe | Niger–Congo | | | 8a · Moribund |
| skiSikabahasa Sikka | ski | Austronesian | | 175,000 | 6a · Vigorous |
| skySikaiana | sky | Austronesian | | | 8a · Moribund |
| ttySikaritaibahasa Aikwakai | tty | — | | | 5 · Developing |
| sipSikkimeseའབྲས་ལྗོངས་སྐད་ | sip | Southern Tibetic | | 70,000 | 4 · Educational |
| skhSikulebahasa Sichule | skh | Austronesian | | | 6b · Threatened |
| sltSila | slt | Sino-Tibetan | | | 6a · Vigorous |
| dauSila language (Chad) | dau | Nilo-Saharan | | | 6a · Vigorous |
| sbqSileibi | sbq | Trans–New Guinea | | | 7 · Shifting |
| szlSilesianŚlůnsko godka | szl | Indo-European | | 457,900 | 5 · Developing |
| sliSilesian Germanschläsche Sproache | sli | Indo-European | | 22,900 | 6a · Vigorous |
| wulSilimobahasa Silimo | wul | — | | | 5 · Developing |
| mkcSiliput | mkc | Torricelli | | | 6b · Threatened |
| sohSillok | soh | Nilo-Saharan | | | 8a · Moribund |
| xspSilopi | xsp | Trans–New Guinea | | | 6b · Threatened |
| sieSimaa | sie | Niger–Congo | | | 6b · Threatened |
| btsSimalungun | bts | Austronesian | | | 5 · Developing |
| sbwSimba | sbw | — | | | 8a · Moribund |
| smgSimbali | smg | East New Britain | | | 6a · Vigorous |
| smbSimbari | smb | — | | | 5 · Developing |
| sbbSimbo | sbb | Austronesian | | | 6a · Vigorous |
| smzSimeku | smz | South Bougainville | | | 6a · Vigorous |
| smrSimeuluebahasa Long Bano | smr | Austronesian | | | 6a · Vigorous |
| smtSimte | smt | Sino-Tibetan | | | 5 · Developing |
| siuSinagen | siu | Torricelli | | | 6b · Threatened |
| sstSinasina | sst | Trans–New Guinea | | | 5 · Developing |
| sncSinaugoro | snc | Austronesian | | 18,000 | 5 · Developing |
| agvSinauna | agv | — | | 2,500 | 8a · Moribund |
| sndSindhiسِنڌِي | snd | Sindhi languages | | 23.8 m | 2 · Provincial |
| sbnSindhi Bhil | sbn | Sindhi languages | | | 6a · Vigorous |
| sgmSinga | sgm | Niger–Congo | | | 10 · Extinct |
| slsSingapore Sign Language | sls | — | | | 5 · Developing |
| sgpSingpho | sgp | Sino-Tibetan | | | 6b · Threatened |
| sinSinhalaසිංහල භාෂාව | sin | Indo-European | | 15.3 m | 1 · National |
| skqSininkere | skq | Niger–Congo | | | 6a · Vigorous |
| rmoSinte Romani | rmo | — | | | 5 · Developing |
| xsiSio | xsi | Austronesian | | | 5 · Developing |
| snnSionaGantëya coca | snn | Tucanoan | | 550 | 7 · Shifting |
| qumSipakapa | qum | Central American Indian languages | | | 6b · Threatened |
| swjSira | swj | Niger–Congo | | | 6a · Vigorous |
| fosSiraya | fos | Austronesian | | | 9 · Dormant |
| ysrSirenik Eskimo | ysr | — | | | 10 · Extinct |
| sirSiri | sir | Afroasiatic | | 3,800 | 8a · Moribund |
| sriSirianoSʉraya | sri | Tucanoan | | 220 | 6b · Threatened |
| srqSirionómbia cheë | srq | — | | 400 | 6b · Threatened |
| srxSirmauri | srx | — | | | 6a · Vigorous |
| ssoSissano | sso | Austronesian | | | 6b · Threatened |
| sisSiuslaw | sis | — | | | 9 · Dormant |
| siySivandi | siy | Indo-European | | | 7 · Shifting |
| lsvSivia Sign Language | lsv | — | | 62 | 6b · Threatened |
| sizSiwa | siz | Afroasiatic | | | 6a · Vigorous |
| akpSiwu | akp | Niger–Congo | | | 5 · Developing |
| skeSke | ske | Austronesian | | | 6b · Threatened |
| skwSkepi Creole Dutch | skw | Dutch-based creole languages | | | 10 · Extinct |
| smsSkolt Saminuõʹrttsääʹmǩiõll | sms | Uralic | | 420 | 7 · Shifting |
| skvSkou | skv | Skou | | | 6a · Vigorous |
| denSlavey | den | Na-Dene | | 2,120 | |
| svmSlavomolisano | svm | Indo-European | | | 7 · Shifting |
| slkSlovakslovenčina | slk | — | +2 | 6 m | 1 · National |
| svkSlovak Sign Language | svk | — | | | 5 · Developing |
| slvSloveneslovenski jezik | slv | Indo-European | +7 | 2.4 m | 1 · National |
| sfmSmall Flowery Miao | sfm | Hmong–Mien | | | 6a · Vigorous |
| kxqSmärky Kanumbahasa Kanum Smarky | kxq | — | | | 6a · Vigorous |
| sssSô | sss | Austroasiatic | | | 6a · Vigorous |
| ssqSo’abahasa So'a | ssq | Austronesian | | 10,000 | 6a · Vigorous |
| sobSobeibahasa Imasi | sob | Austronesian | | | 7 · Shifting |
| csoSochiapam Chinantec | cso | Central American Indian languages | | | 5 · Developing |
| gruSoddo | gru | Afroasiatic | | | |
| xogSoga | xog | Niger–Congo | | | 5 · Developing |
| sogSogdian | sog | Indo-European | | | |
| sojSoi | soj | Indo-European | | | 6b · Threatened |
| swnSokna | swn | Afroasiatic | | | 10 · Extinct |
| socSoko | soc | Niger–Congo | | | 6a · Vigorous |
| sokSokoro | sok | Afroasiatic | | | 6a · Vigorous |
| sbySoli | sby | — | | 54,400 | 6a · Vigorous |
| szsSolomon Islands Sign Language | szs | — | | | 6a · Vigorous |
| aawSolong | aaw | Austronesian | | | 4 · Educational |
| solSolos | sol | Austronesian | | | 5 · Developing |
| smcSom | smc | Trans–New Guinea | | | 7 · Shifting |
| somSomaliAf-Soomaali | som | Afroasiatic | +1 | 16.2 m | 1 · National |
| sorSomrai | sor | Afroasiatic | | | 5 · Developing |
| smuSomray | smu | Austroasiatic | | | 8a · Moribund |
| kgtSomyev | kgt | Niger–Congo | | | 8b · Nearly Extinct |
| shcSonde | shc | Niger–Congo | | | 6a · Vigorous |
| sopSonge | sop | Niger–Congo | | | 6a · Vigorous |
| sooSongo | soo | Niger–Congo | | | 6a · Vigorous |
| soiSonha | soi | Indo-European | | | 6b · Threatened |
| snkSoninkeSooninkanxanne | snk | Niger–Congo | +4 | 1.1 m | 5 · Developing |
| sozSonjo | soz | Niger–Congo | | | 6a · Vigorous |
| sovSonsoroleseramari Dongosaro | sov | Austronesian | | 600 | 6b · Threatened |
| teuSoo language | teu | Nilo-Saharan | | 50 | 8b · Nearly Extinct |
| sqtSoqotri | sqt | Afroasiatic | | | 8a · Moribund |
| srbSora | srb | Austroasiatic | | 410,000 | 5 · Developing |
| sbhSori-Harengan | sbh | Austronesian | | | 6a · Vigorous |
| sqoSorkhei | sqo | Indo-European | | | 6a · Vigorous |
| sdkSos Kundi | sdk | Sepik | | | 5 · Developing |
| bsiSosi | bsi | Niger–Congo | | | 6a · Vigorous |
| krzSota Kanumbahasa Kanum Sota | krz | — | | | 6a · Vigorous |
| bszSouletinZuberera | bsz | Paleo-European languages | | | |
| sfsSouth African Sign Language | sfs | — | | | 5 · Developing |
| awsSouth Awyubahasa Awyu selatan | aws | Trans–New Guinea | | | 6b · Threatened |
| azbSouth Azerbaijaniتورك ديلی | azb | Turkic | | 14.6 m | 3 · Wider Communication |
| quhSouth Bolivian QuechuaQullasuyu qhichwa simi | quh | Quechua | | 1.6 m | 5 · Developing |
| lnlSouth Central Banda | lnl | Niger–Congo | | | 6a · Vigorous |
| dibSouth Central Dinka | dib | Nilo-Saharan | | | 4 · Educational |
| erkSouth Efate | erk | Austronesian | | | 5 · Developing |
| vroSouth Estonian | vro | Uralic | | 80,000 | Definitely endangered |
| falSouth Fali | fal | Niger–Congo | | | 5 · Developing |