unrounded

Unrounded is a term used in phonetics and phonology to describe vowels that are articulated without lip rounding. In descriptions of vowel inventories, unrounded vowels are often assumed to have a spread or neutral lip posture, contrasted with rounded vowels in which the lips are pursed. The feature is commonly represented in phonological analyses as [-round], even though IPA transcriptions typically encode rounding directly in the vowel symbol (for example, i is unrounded, while y is rounded).

The distinction between unrounded and rounded vowels is phonetic and perceptual as well as phonological. Lip rounding affects the acoustic qualities of vowels, including formant frequencies and spectral tilt, and it can interact with height, backness, and vowel harmony in a language. Rounding can be a stable phonemic contrast in some languages, while in others it is largely predictable from other vowel features.

Cross-linguistic patterns vary. Many languages have front vowels that are unrounded (such as i and e) and back vowels that are rounded (such as u and o), though there are languages with back unrounded vowels as well. Some languages contrast rounded and unrounded vowels in the same height and backness, producing pairs like i vs y or e vs ø in German and French. Others merge rounding distinctions or rely on rounding in consonants rather than vowels.

In linguistic descriptions, the concept supports analyses of vowel inventories, vowel harmony, and phonological rule systems. While the phonetic reality of rounding is continuous, the unrounded/rounded dichotomy offers a practical binary in many descriptive frameworks.