labio-dental (adj./n.)

A term used in the PHONETIC classification of speech sounds on the basis of their PLACE OF ARTICULATION: it refers to a sound in which one lip is actively in contact with the teeth. The usual mode of operation for a labio-dental sound (‘a labio-dental’) is for the lower lip to articulate with the upper teeth, as in [f] and [v]. The opposite effect, upper lip against lower teeth, is possible in theory, but not recognized in the usual phonetic classifications. The term is also applied to articulations where the lip approaches close to the teeth, but without actual contact, as in the sound , which is a VOWEL-like sound midway between [w] and [v].