Yu (Cyrillic)

Sometimes, it is referred to as "Iotated U" because it is a so-called iotated vowel, pronounced in isolation as /ju/, like the pronunciation of ⟨u⟩ in "human". After a consonant, no distinct [j] sound is pronounced, but the consonant is softened. The exact pronunciation of the vowel sound of ⟨ю⟩ in Slavic languages depends also on the succeeding sound. Before a soft consonant, it is [ʉ], the close central rounded vowel, as in 'rude'. Before a hard consonant or at the end of a word, the result is a back vowel [u], as in "pool".

Apart from the form I-O, in early Slavonic manuscripts the letter appears also in a mirrored form O-I (Ꙕ, ꙕ). As to its origin: One possibility is that it was derived from the omicron-iota (οι) diphthong. At the time that the Greek alphabet was adapted to the Slavonic language, it denoted the close front rounded vowel /y/ in educated Greek speech. The close front rounded vowel does not appear in East Slavic, thus its approximation would have given way to the letters' modern pronunciation.

There is another possible origin to the modern form. By the analogy to several 'iotated' letters Ѥ, Ꙗ, Ѩ and Ѭ; the iotated version of the archaic Cyrillic digraph (or letter) Uk ⟨І-оѵ⟩/⟨І-оу⟩ could have possibly been derived into the modern letter ⟨ю⟩ through the omission of the latter glyph of the trigraphs, similar to how the modern letter У was derived.

The iotated big Yus ⟨Ѭ⟩ merged itself to ⟨ю⟩ in East Slavic languages.

⟨Ю⟩ is the Voice Quality Symbol for tracheo-œsophageal speech (the symbol attempts to capture iconically the dual nature of the airstream).

• У у : Cyrillic letter U
• Ү ү : Cyrillic letter Ue
• Û û : Latin letter U with circumflex
• Ū ū : Latin letter U with macron
• Ǔ ǔ : Latin letter U with caron