Yus

Little yus (Ѧ, ѧ; italics: Ѧ, ѧ; Church Slavonic: юсъ малыи, romanized: jusъ malyi) and big yus (Ѫ, ѫ; italics: Ѫ, ѫ; Church Slavonic: юсъ большии, romanized: jusъ bolьšii), or jus, are letters of the Cyrillic script representing two Common Slavonicnasal vowels in the early Cyrillic and Glagolitic alphabets. Each can occur in iotated form (Ѩ ѩ, Ѭ ѭ), formed as ligatures with the decimal i (І).

Phonetically, little yus represents a nasalized front vowel, possibly [ɛ̃] (like the French ‘in’ in “cinq” or Polish 'ę' in “kęs”), while big yus represents a nasalized back vowel, such as IPA [ɔ̃] (like the French ‘on’ in “bombon” or Polish 'ą' in “kąt”).

The names of the letters do not imply capitalization, as both little and big yus exist in majuscule and minuscule variants.

Other yus letters like the closed little yus (Ꙙ ꙙ), iotated closed little yus (Ꙝ ꙝ) and blended yus (Ꙛ ꙛ), were also used historically.

Closed little yus is found in Old Church Slavonic and Middle Bulgarian manuscripts, where it may be used contrastively with little yus. In the Codex Supraslensis, for example, little yus represents [jɛ̃] and the closed version represents [ɛ̃].

Blended yus is found in certain Middle Bulgarian manuscripts where it replaces (and eliminates) both little and big yus.