|Northern Yi, Liangshan Yi, Sichuan Yi|
|Region||Southern Sichuan, northern Yunnan|
|2 million (2000 census)|
Liangshan (Cool Mountain) dialect
|Yi syllabary, formerly Yi logograms|
Nuosu or Nosu (, pronunciation: Nuosuhxop), also known as Northern Yi, Liangshan Yi, and Sichuan Yi, is the prestige language of the Yi people; it has been chosen by the Chinese government as the standard Yi language (in Mandarin: Yí y?, /) and, as such, is the only one taught in schools, both in its oral and written forms. It was spoken by two million people and was increasing as of (PRC census); 60% were monolingual (1994 estimate). Nuosu is the native Nuosu/Yi name for their own language and is not used in Mandarin Chinese; although it may sometimes be spelled out for pronunciation (nuòs? y? /), the Chinese characters for nuòs? have no meaning.
The occasional terms 'Black Yi' (Mandarin: h?i Yí ) and 'White Yi' (bái Yí ) are castes of the Nuosu people, not dialects.
Nuosu is one of several often mutually unintelligible varieties known as Yi, Lolo, Moso, or Noso; the six Yi languages recognized by the Chinese government hold only 25% to 50% of their vocabulary in common. They share a common traditional writing system, though this is used for shamanism rather than daily accounting.
Lama (2012) gives the following classification for Nuosu dialects.
The Qumusu (Tianba ) dialect is the most divergent. The other dialects group as Niesu (Suondi and Adu) and as Nuosu proper (Muhisu , Yinuo , and Shengzha ). Niesu has lost voiceless nasals and has developed diphthongs.
Adu , characterized by its labial-velar consonants, is spoken in Butuo County and Ningnan County of Liangshan Yi Autonomous Prefecture, Sichuan province, and also in parts of Puge County , Zhaojue County , Dechang County , and Jinyang County (Pan 2001).
Zhu & Zhang (2005) reports that the Shuitian people () reside mostly in the lowlands of the Anning River drainage basin, in Xichang, Xide, and Mianning counties of Liangshan Prefecture in Sichuan. They are called Muhisu (mu33 hi44 su33) by the neighboring Yi highland people. Shuitian is spoken in the following locations. Shuitian belongs to the Shengzha dialect () of Northern Yi.
According to Bradley (1997), there are 3 main dialects of Nosu, of which the Southeastern one (Sondi) is most divergent.
Chen (2010) lists the following dialects of Nosu. Also listed are the counties where each respective dialect is spoken.
The Modern Yi script (? nuosu bburma [ns? bm?] 'Nosu script') is a standardized syllabary derived from the classic script in 1974 by the local government of China. It was made the official script of the Yi languages in 1980. There are 756 basic glyphs based on the Liangshan dialect, plus 63 for syllables only found in Chinese borrowings.
The written equivalents of the phonemes listed here are "Yi Pinyin". For information about the actual script used see the section above entitled Writing System.
|Nasal||voiced||m /m/||n /n/||ny /?/||ng /?/|
|unvoiced||hm /m?/||hn /n?/|
|Plosive||prenasalized||nb /?b/||nd /?d/||mg //|
|voiced||bb /b/||dd /d/||gg /?/|
|unvoiced||b /p/||d /t/||g /k/|
|aspirated||p /p?/||t /t?/||k /k?/|
|Affricate||prenasalized||nz /?dz/||nr //||nj //|
|voiced||zz /dz/||rr //||jj //|
|unvoiced||z /ts/||zh //||j //|
|aspirated||c /ts?/||ch //||q //|
|Fricative||unvoiced||f /f/||s /s/||sh /?/||x /?/||h /x/||hx /h/|
|voiced||v /v/||ss /z/||r /?/||y /?/||w /?/|
|loose||y /z?/||u /v/|
|tight||yr /z?/||ur /v??/|
|Near-close||loose||i /e?/||e //||o /o?/|
|Open-mid||tight||ie /?/||uo /?/|
Nuosu has five pairs of phonemic vowels, contrasting in a feature Eatough calls loose throat vs. tight throat. Underlining is used as an ad-hoc symbol for tight throat; phonetically, these vowels are laryngealized and/or show a retracted tongue root. Loose vs. tight throat is the only distinction in the two pairs of syllabic consonants, but in the vocoids it is reinforced by a height difference.
The syllabic consonants y(r) u(r) are essentially the usual Sinological vowels ? ?, so y can be identified with the vowel of the Mandarin ? sì "four", but they have diverse realizations. Y(r) completely assimilates to a preceding coronal except in voice, e.g. /?z/  "to marry", and are [m?l?] after a labial nasal, e.g. /m?zsz/ [m?m?lsz] "cloth". U(r) assimilates similarly after laterals, retaining its rounding, e.g. /l?v/ [l?l] "to stir-fry", and is [m] after a labial nasal, e.g. /m?v/ [m?m] "mushroom"; moreover it induces a labially trilled release of preceding labial or alveolar stops, e.g. /?dv?/ [?d?v?] "to hit".
The tight-throat phone  occurs as the realization of // in the high tone. That it is phonemically loose-throat is shown by its behaviour in tightness harmony in compound words.
The high-mid tone is only marginally contrastive. Its two main sources are from tone sandhi rules, as the outcome of a mid tone before another mid tone, and the outcome of a low-falling tone after a mid tone. However, these changes do not occur in all compounds where they might: for instance wo "bear" + mop "mother" regularly forms wo mox "female bear", but vi "jackal" + mop "mother" forms vi mop "female jackal" without sandhi. The syntax creates other contrasts: tone sandhi applies across the boundary between object and verb, so is present in SOV clauses like mu jy lu ti shex "Mujy looks for Luti", but is absent in OSV clauses like mu jy lu ti shep "Luti looks for Mujy". A few words, like xix "what?", have underlying high-mid tone.