sibilant
1. [ adjective ] of speech sounds produced by forcing air through a constricted passage (as `f', `s', `z', or `th' in both `thin' and `then')
Synonyms: spirant fricative
Related terms: soft
2. [ noun ] (linguistics,phonetics) a consonant characterized by a hissing sound (like s or sh)
Synonyms: sibilant_consonant
Related terms: consonant sibilate sibilate hiss