"sibilant" in the noun sense
1. sibilant, sibilant consonant
a consonant characterized by a hissing sound (like s or sh)
"sibilant" in the adjective sense
1. fricative, continuant, sibilant, spirant, strident
of speech sounds produced by forcing air through a constricted passage (as `f', `s', `z', or `th' in both `thin' and `then')
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License