Vowel

A vowel is a speech sound in spoken language which is pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis.

There are three kinds of vowel sounds: monophthongs, diphthongs and triphthongs.

For historical reasons there is a large mismatch between the number of vowels in English - which has up to twenty vowels (depending on the accent) - and the vowel letters, which are limited to A, E, I, O, U, and in some cases, Y.

For a description of the vowels in English see Phonetic symbol § Vowels.