Editing Vowel (section)

== Monophthongs, diphthongs, triphthongs ==
{{Main|Monophthong|Diphthong|Triphthong|Semivowel}}
A vowel sound whose quality does not change throughout the vowel is called a [[monophthong]]. Monophthongs are sometimes called "pure" or "stable" vowels. A vowel sound that glides from one quality to another is called a [[diphthong]], and a vowel sound that glides successively through three qualities is a [[triphthong]].

All languages have monophthongs and many languages have diphthongs, but triphthongs or vowel sounds with even more target qualities are relatively rare cross-linguistically. English has all three types: the vowel sound in ''hit'' is a monophthong {{IPA|/ɪ/}}, the vowel sound in ''boy'' is in most dialects a diphthong {{IPA|/ɔɪ/}}, and the vowel sounds of ''flower'', {{IPA|/aʊər/}}, form a triphthong or disyllable, depending on the dialect.

In [[phonology]], diphthongs and triphthongs are distinguished from sequences of monophthongs by whether the vowel sound may be analyzed into distinct [[phonemes]]. For example, the vowel sounds in a two-syllable pronunciation of the word ''flower'' ({{IPA|/ˈflaʊər/}}) phonetically form a disyllabic triphthong but are phonologically a sequence of a diphthong (represented by the letters {{angle bracket|ow}}) and a monophthong (represented by the letters {{angle bracket|er}}). Some linguists use the terms ''diphthong'' and ''triphthong'' only in this phonemic sense.