Previously considered a single "Mordvin language",[8]
it is now treated as a small language grouping.[9] Due to differences in phonology, lexicon, and grammar, Erzya and Moksha are not mutually intelligible.[10] The two Mordvinic languages also have separate literary forms. The Erzya literary language was created in 1922 and the Mokshan in 1923.[11]
Phonological differences between the two languages include:[8]
Moksha retains a distinction between the vowels /ɛ,e/ while in Erzya, they have merged as /e/.
In unstressed syllables, Erzya features vowel harmony like many other Uralic languages, using [e] in front-vocalic words and [o] in back-vocalic words. Moksha has a simple schwa[ə] in their place.
Word-initially, Erzya has a postalveolar affricate /tʃ/ corresponding to a fricative /ʃ/ in Moksha.
Next to voiceless consonants, liquids/r,rʲ,l,lʲ/ and the semivowel/j/ are devoiced in Moksha to [r̥r̥ʲl̥l̥ʲȷ̊].
^Hamari, Arja; Ajanki, Rigina (2022). "Mordvin (Erzya and Moksha)". In Marianne Bakró-Nagy; Johanna Laakso; Elena Skribnik (eds.). The Oxford Guide to the Uralic Languages. Oxford University Press. pp. 392–431.
^Феоктистов А. П. Мордовские языки. основы финно-угорского языкознания. Прибалтийско-финские, саамский и мордовские языки. М., 1975