a. (in English articulation) a speech sound produced without occluding, diverting, or obstructing the flow of air from the lungs ( opposed to consonant ).
b. (in a syllable) the sound of greatest sonority, as i in grill. Compare consonant ( def 1b ) .
c.(in linguistic function) a concept empirically determined as a phonological element in structural contrast with consonant, as the (Ä“) of be (bÄ“), we (wÄ“), and yeast (yÄ“st).
2.a letter representing or usually representing a vowel, as, in English, a, e, i, o, u, and sometimes w and y.