| muuYaaku | muu | — | | | 8a · Moribund |
| yarYabarana | yar | Cariban | | 20 | 8a · Moribund |
| jaeYabem | jae | Austronesian | | | 6b · Threatened |
| ybmYaben | ybm | Trans–New Guinea | | | 6a · Vigorous |
| ekrYace | ekr | Niger–Congo | | | 6a · Vigorous |
| rysYaeyama | rys | Japonic | | 47,600 | 7 · Shifting |
| ygrYagaria | ygr | Trans–New Guinea | | 21,000 | 5 · Developing |
| yagYaghanHáusi Kúta | yag | — | | | 8b · Nearly Extinct |
| yaiYaghnobiйағнобӣ зӣвок | yai | Indo-European | | 12,000 | 6b · Threatened |
| yadYaguaNijyamïï Nikyejaada | yad | Saparo–Yawan | | 5,700 | 6b · Threatened |
| rhpYahang | rhp | Torricelli | | | 6b · Threatened |
| yafYaka | yaf | Niger–Congo | | | 6a · Vigorous |
| ykkYakaikeke | ykk | Austronesian | | | 6b · Threatened |
| yakYakama | yak | Plateau Penutian | | | 8b · Nearly Extinct |
| ykmYakamul | ykm | Austronesian | | | 6b · Threatened |
| ykaYakan | yka | Austronesian | | 110,000 | 4 · Educational |
| ybhYakkha | ybh | Sino-Tibetan | | | 6b · Threatened |
| ykyYakoma | yky | Niger–Congo | | 110,000 | 6a · Vigorous |
| sahYakutСаха тыла | sah | Turkic | | 450,000 | 2 · Provincial |
| ybaYala | yba | Niger–Congo | | 200,000 | 5 · Developing |
| jalYalahatan | jal | Austronesian | | 1,700 | 6b · Threatened |
| zpuYalálag Zapotec | zpu | Central American Indian languages | | | 5 · Developing |
| ylrYalarnnga | ylr | Australian Aboriginal languages | | | 10 · Extinct |
| nceYalë | nce | — | | 600 | 5 · Developing |
| yalYalunka | yal | Niger–Congo | +1 | | 5 · Developing |
| yamYamba | yam | Niger–Congo | | | 5 · Developing |
| ynbYamben | ynb | Trans–New Guinea | | | |
| yatYambeta | yat | Niger–Congo | | | 6b · Threatened |
| jmdYamdenabahasa Yamdena | jmd | Austronesian | | 30 | 5 · Developing |
| ymeYameoNijyamïï Nikyejaada | yme | Saparo–Yawan | | | 10 · Extinct |
| taoYamiciriciring no Tao | tao | Austronesian | | 3,800 | 6b · Threatened |
| yaaYaminawa | yaa | Pano-Tacanan | | 2,729 | 5 · Developing |
| ymnYamna | ymn | Austronesian | | | 8a · Moribund |
| ybiYamphu | ybi | Sino-Tibetan | | | 6b · Threatened |
| ynnYana | ynn | — | | | |
| ydaYanda | yda | Australian Aboriginal languages | | | 10 · Extinct |
| dymYanda Dogon | dym | Niger–Congo | | | 6a · Vigorous |
| yndYandruwandha | ynd | Australian Aboriginal languages | | | 10 · Extinct |
| ameYanesha' | ame | — | | | 5 · Developing |
| zygYang Zhuang | zyg | Kra–Dai | | | 6a · Vigorous |
| tjjYangathimri | tjj | Australian Aboriginal languages | | | 8b · Nearly Extinct |
| yavYangben | yav | Niger–Congo | | | 6b · Threatened |
| yngYango | yng | Niger–Congo | | | 6a · Vigorous |
| ydeYangum Dey | yde | Torricelli | | | 6b · Threatened |
| yglYangum Gel | ygl | Torricelli | | | 6b · Threatened |
| bsxYankam | bsx | Niger–Congo | | | 8b · Nearly Extinct |
| kddYankunytjatjara | kdd | Australian Aboriginal languages | | 600 | 8a · Moribund |
| guuYanomamöYanomamɨ | guu | Yanomaman | | 16,200 | 5 · Developing |
| ynsYansi | yns | Niger–Congo | | | 6a · Vigorous |
| jaoYanyuwa | jao | Australian Aboriginal languages | | | 7 · Shifting |
| yaoYaochiYao | yao | Niger–Congo | | | 5 · Developing |
| yapYapeseWa'ab | yap | Austronesian | | 5,130 | 2 · Provincial |
| yevYapunda | yev | Torricelli | | | 7 · Shifting |
| yaqYaqui | yaq | Uto-Aztecan | | | 8a · Moribund |
| yrwYarawata | yrw | Trans–New Guinea | | | 8a · Moribund |
| yrbYareba | yrb | Trans–New Guinea | | | 5 · Developing |
| yryYarluyandi | yry | Australian Aboriginal languages | | | 9 · Dormant |
| yroYaroamë | yro | Yanomaman | | 430 | 6a · Vigorous |
| yrsYarsun | yrs | — | | | 8a · Moribund |
| yaeYaruro | yae | — | | | 6a · Vigorous |
| ykoYasa | yko | Niger–Congo | | | 5 · Developing |
| zavYatzachi Zapotec | zav | Central American Indian languages | | 2,500 | 6b · Threatened |
| yuwYau | yuw | — | | | 5 · Developing |
| yyuYau | yyu | Torricelli | | | 6b · Threatened |
| ylaYaul | yla | Mongol–Langam | | | 6a · Vigorous |
| ynuYauna | ynu | Tucanoan | | 95 | 9 · Dormant |
| jauYaur | jau | — | | | 7 · Shifting |
| quxYauyos–Chincha QuechuaYawyu runasimi | qux | Quechua | | 13,000 | 8a · Moribund |
| zpdYavesía Zapotec | zpd | Central American Indian languages | | | 6b · Threatened |
| yvtYavitero | yvt | Northern Maipuran | | | 10 · Extinct |
| yvaYawabahasa Yawa | yva | — | | 10,000 | 5 · Developing |
| yawYawalapití | yaw | Paresi–Waura | | 8 | 8b · Nearly Extinct |
| ywnYawanawa | ywn | Pano-Tacanan | | | 6a · Vigorous |
| ywwYawarawarga | yww | Australian Aboriginal languages | | | 10 · Extinct |
| jbwYawijibaya | jbw | Worrorran | | | 9 · Dormant |
| ybxYawiyo | ybx | Walio | | | 6b · Threatened |
| ywrYawuru | ywr | Nyulnyulan | | 6 | 9 · Reawakening |
| xyaYaygir | xya | Australian Aboriginal languages | | 5 | 10 · Extinct |
| yahYazgulyamyuzdami zevég | yah | Indo-European | | 3,300 | 6b · Threatened |
| mchYe'kuana | mch | Cariban | | 6,000 | 6a · Vigorous |
| bdmYedina | bdm | Afroasiatic | | | 6a · Vigorous |
| jeiYeibahasa Yei | jei | — | | | 7 · Shifting |
| etsYekhee | ets | Niger–Congo | | | 6a · Vigorous |
| yelYela | yel | Niger–Congo | | | 6a · Vigorous |
| yleYele | yle | — | | 5,000 | 5 · Developing |
| jelYelmekbahasa Jab | jel | — | | | 8a · Moribund |
| ylgYelogu | ylg | Sepik | | | 6b · Threatened |
| jnjYem | jnj | Afroasiatic | | | 4 · Educational |
| ybbYemba | ybb | Niger–Congo | | | 5 · Developing |
| ynqYendang | ynq | Niger–Congo | | | 6a · Vigorous |
| yeiYeni | yei | — | | | 10 · Extinct |
| yecYenish | yec | Indo-European | +1 | 16,000 | 6a · Vigorous |
| yraYerakai | yra | — | | | 6b · Threatened |
| gopYeretuarbahasa Goni | gop | Austronesian | | | 7 · Shifting |
| yrnYerong | yrn | Kra–Dai | | | 6b · Threatened |
| yeuYerukala | yeu | Dravidian | | | 5 · Developing |
| yssYessan | yss | Sepik | | | 5 · Developing |
| yetYetfabahasa Biaksi | yet | — | | | 3 · Wider Communication |
| yejYevanic | yej | — | | | 8b · Nearly Extinct |
| yeyYeyi | yey | Niger–Congo | | 24,000 | 6b · Threatened |
| yidYiddishיידיש | yid | Indo-European | +26 | 1 m | Definitely endangered |
| ydgYidgha | ydg | Indo-European | | 6,150 | 6b · Threatened |
| yiiYidiny | yii | Australian Aboriginal languages | | 52 | 8b · Nearly Extinct |
| ayiYigha | ayi | Niger–Congo | | | 6a · Vigorous |
| yllYil | yll | Torricelli | | | 6a · Vigorous |
| ycrYilan Creole JapaneseKankei | ycr | — | | | 8a · Moribund |
| yeeYimas | yee | Ramu–Lower Sepik | | 300 | 6b · Threatened |
| yimYimkhiungrü | yim | Sino-Tibetan | | 83,259 | 5 · Developing |
| yinYinchia | yin | Austroasiatic | | | 6b · Threatened |
| yilYindjilandji | yil | Australian Aboriginal languages | | | 10 · Extinct |
| pibYine | pib | Piro | | 5,000 | 5 · Developing |
| yiaYinggarda | yia | Australian Aboriginal languages | | | 9 · Dormant |
| ywgYinhawangka | ywg | Australian Aboriginal languages | | | 8b · Nearly Extinct |
| yijYinjibarndi | yij | Australian Aboriginal languages | | 377 | 6a · Vigorous |
| kvyYintale | kvy | Sino-Tibetan | | 1,000 | 6b · Threatened |
| yxmYinwum | yxm | Australian Aboriginal languages | | | 10 · Extinct |
| byrYipma | byr | — | | 6,600 | 5 · Developing |
| yiyYir-Yoront | yiy | Australian Aboriginal languages | | | 9 · Dormant |
| ljwYirandhali | ljw | Australian Aboriginal languages | | | 10 · Extinct |
| yrmYirrk-Thangalkl | yrm | Australian Aboriginal languages | | | 9 · Dormant |
| yisYis | yis | Torricelli | | | 6b · Threatened |
| xthYitha Yitha | xth | Australian Aboriginal languages | | | 9 · Dormant |
| yobYoba | yob | — | | | 10 · Extinct |
| soyYobe | soy | Niger–Congo | | | 5 · Developing |
| yogYogad | yog | — | | 16,000 | 6a · Vigorous |
| ykiYokebahasa Pauwi | yki | Austronesian | | | 6b · Threatened |
| yokYokuts | yok | — | | | 8a · Moribund |
| yolYola | yol | Indo-European | | 140 | Extinct |
| scpYolmo | scp | — | | 10,000 | 6b · Threatened |
| ygsYolŋu Sign Language | ygs | — | | | 6a · Vigorous |
| pilYom | pil | Niger–Congo | | | 5 · Developing |
| yomYombe | yom | Niger–Congo | | | 5 · Developing |
| yoiYonaguni与那国物言 | yoi | Japonic | | 400 | 7 · Shifting |
| zybYongbei Zhuang | zyb | Kra–Dai | | 2 m | 6a · Vigorous |
| yonYonggom | yon | Trans–New Guinea | | | 5 · Developing |
| yutYopno | yut | — | | | 5 · Developing |
| mtsYora | mts | Pano-Tacanan | | | 6a · Vigorous |
| yoxYoronユンヌフトゥバ | yox | Japonic | | | 7 · Shifting |
| xyyYorta Yorta | xyy | Australian Aboriginal languages | | | 10 · Extinct |
| yorYorubaÈdè Yorùbá | yor | Niger–Congo | | 40 m | 2 · Provincial |
| jiuYoule Jinuo | jiu | Sino-Tibetan | | | 6b · Threatened |
| gekYoum | gek | Afroasiatic | | | 6a · Vigorous |
| buhYounuo | buh | Hmong–Mien | | | 7 · Shifting |
| nuaYuanga | nua | Austronesian | | | 6b · Threatened |
| yuaYucatec Mayamàaya t'àan | yua | Central American Indian languages | | 706,000 | 5 · Developing |
| msdYucatec Maya Sign Language | msd | — | | | 6a · Vigorous |
| yucYuchi | yuc | — | | | 8b · Nearly Extinct |
| ycnYucuna | ycn | Upper Amazon Arawakan | | 1,800 | 5 · Developing |
| yueYue Chinese粵語 | yue | Sino-Tibetan | | 62.2 m | 2 · Provincial |
| yubYugambal | yub | Australian Aboriginal languages | | | 10 · Extinct |
| xjbYugambeh | xjb | Australian Aboriginal languages | | 208 | 10 · Extinct |
| yugYugh | yug | Yeniseian | | 1 | 8b · Nearly Extinct |
| yslYugoslav Sign Language | ysl | — | | | 5 · Developing |
| yguYugul | ygu | Australian Aboriginal languages | | | 10 · Extinct |
| yabYuhup | yab | Nadahup | | 400 | 5 · Developing |
| yukYuki | yuk | — | | | 9 · Dormant |
| yupYukpa | yup | Cariban | | 7,500 | 6b · Threatened |
| yblYukuben | ybl | Niger–Congo | | | 6a · Vigorous |
| gcdYukulta | gcd | Macro-Pama–Nyungan | | | 9 · Dormant |
| yulYulu | yul | Nilo-Saharan | | 13,000 | 6b · Threatened |
| yuqYuqui | yuq | — | | | 7 · Shifting |
| yuzYuracaré | yuz | — | | 2,500 | 7 · Shifting |
| rtsYurats | rts | Uralic | | | |
| yurYurok | yur | Algic | | 12 | 9 · Dormant |
| ljxYuru | ljx | Australian Aboriginal languages | | | 10 · Extinct |
| yxuYuyu | yxu | Australian Aboriginal languages | | | 9 · Dormant |