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A monophthong (/ˈmɒnəfθɒŋ/,MON-əf-thong) is avowel sound characterized by a relatively stable articulatory configuration throughout its duration. During the production of a monophthong, the tongue does not undergo significant vertical (height) or horizontal (front–back) movement toward a different position ofarticulation. For this reason, monophthongs are commonly referred to as pure vowels.
Monophthongs are contrasted withdiphthongs, in which vowel quality changes (or glides) within a single syllable, and withhiatus, in which two adjacent vowel sounds belong to separate syllables.
The term derives from Ancient Greekμονόφθογγος (monóphthongos, “single sound”), formed fromμόνος (mónos, “single”) andφθόγγος (phthóngos, “sound”).[1]
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The processes by which monophthongs develop into diphthongs (diphthongization), and by which diphthongs simplify into monophthongs (monophthongization), constitute important mechanisms oflanguage change. These developments frequently interact with broader phonological shifts and may result in systemic changes to vowel inventories.
In a number of languages, historical monophthongization has causedgraphemes that originally represented diphthongs to be reinterpreted as denoting monophthongal vowel sounds.
