'Sibilant' definitions:

Definition of 'sibilant'

(from WordNet)
adjective
Of speech sounds produced by forcing air through a constricted passage (as `f', `s', `z', or `th' in both `thin' and `then') [syn: fricative, continuant, sibilant, spirant, strident]
noun
A consonant characterized by a hissing sound (like s or sh) [syn: sibilant, sibilant consonant]

Definition of 'Sibilant'

From: GCIDE
  • Sibilant \Sib"i*lant\, a. [L. sibilans, -antis, p. pr. of sibilare to hiss: cf. F. sibilant.] Making a hissing sound; uttered with a hissing sound; hissing; as, s, z, sh, and zh, are sibilant elementary sounds. -- n. A sibiliant letter. [1913 Webster]