In the International Phonetic Alphabet, it represents the open-mid back rounded vowel.

The Yucatec Maya language used Ɔ to transcribe the alveolar ejective affricate [t͡sʼ] consonant in the orthography of the Colonial period.

Claudius introduced a Ɔ (the antisigma) with the intention of replacing bs and ps.

The Scandinavian explanatory symbol (forklaringstegnet) can be typeset using the open o followed by a colon, thus: ɔ:.

[4] This letter is often used to refer to the Copyleft official sign, which looks like an open o with a circle around it.