1. any of the set of distinctive sounds of a given language. Cf. phoneme.
2. any audible, elemental, acoustic event occurring in speech: “Go” contains the speech sound “o.” Cf. phone 2.
3. any of the sounds of the entire phonetic system of a language. Cf. allophone.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.