In some other languages (such as Bengali and Luxembourgish)[7][8] as well as some dialects of English (such as Scottish)[9][10] there is a fully back near-close rounded vowel (a sound between cardinal [u] and [o]), which can be transcribed in IPA with ⟨ʊ̠⟩, ⟨u̞⟩ or ⟨o̝⟩.

The near-close back protruded vowel is typically transcribed in IPA simply as ⟨ʊ⟩, and that is the convention used in this article.

Because back rounded vowels are assumed to have protrusion, and few descriptions cover the distinction, some of the following may actually have compression.

Some languages, such as Norwegian, are found with a near-close back vowel that has a distinct type of rounding, called compressed or exolabial.

The spread-lip diacritic ⟨  ͍⟩ may also be used with a rounded vowel letter ⟨ʊ͍⟩ as an ad hoc symbol, though technically 'spread' means unrounded.