monoftong

A monoftong, in phonetics and phonology, is a vowel sound that maintains a single, unchanging quality throughout its duration. It contrasts with a diphthong, which involves a glide from one vowel quality to another within the same syllable. A monoftong is often described as a pure or simple vowel.

Phonetically, a monoftong should show little or no movement in the tongue height, backness, or lip rounding during articulation. In IPA notation, common monophthongs include short or long vowels such as [i], [e], [a], [o], and [u], as well as their lengthened forms like [iː] or [uː]. The key criterion is stability of the vowel's acoustic quality over time.

Languages vary in their use of monophthongs and diphthongs. Some languages, such as Spanish, Italian, and Finnish, are noted for having relatively extensive sets of clear, stable monophthongs. Others, like many varieties of English, contain numerous diphthongs and may also exhibit vowel qualities that behave as monophthongs in certain phonological analyses. In some cases, historical diphthongs undergo monophthongization, a sound change in which a complex vowel becomes a single, pure vowel.

In linguistic analysis, the distinction between monophthongs and diphthongs helps describe how vowels function as phonemic units and how they interact with syllable structure, stress, and surrounding consonants.