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).^[1] 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.^{[citation needed]}

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.^[1]

The iotated big Yus ⟨Ѭ⟩ merged itself to ⟨ю⟩ in East Slavic languages.^{[citation needed]}

⟨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