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c.1300, from Old French vouel, from Latin vocalis, in littera vocalis, literally "vocal letter," from vox (genitive vocis) "voice" (see voice (n.)). Vowel shift in reference to the pronunciation change between Middle and Modern English is attested from 1909. The Hawaiian word hooiaioia, meaning "certified," has the most consecutive vowels of any word in current human speech; the English record-holder is queueing.
Letters of the alphabet that generally stand for sounds made with an open or partially open mouth: A, E, I, O, U, and sometimes Y (as in style). (Compare consonants.)