fricative

Produced by the friction or rustling of the breath, intonated or unintonated, through a narrow opening between two of the mouth organs; uttered through a close approach, but not with a complete closure, of the organs of articulation, and hence capable of being continued or prolonged; -- said of certain consonantal sounds, as f, v, s, z, etc.

of speech sounds produced by forcing air through a constricted passage (as `f', `s', `z', or `th' in both `thin' and `then')

a continuant consonant produced by breath moving against a narrowing of the vocal tract