Ɯ

Ɯ (minuscule: ɯ) is a letter of the Latin alphabet, shaped like a rounded W (or, more accurately, a rotated m).

It is also used in the International Phonetic Alphabet, to represent a close back unrounded vowel.

Ɯ was used in the Zhuang alphabet from 1957 to 1986 to represent the same vowel in IPA; sometime before or in 1986, it was replaced with W.

In Cyrillic, the lowercase letter sha in italic type resembles ɯ. Since Zhuang borrowed heavily from Cyrillic forms for several letters of its alphabet, it is plausible that sha was the source of the Zhuang letter.