sibilant vs fricative

sibilant and fricative both are nouns.

Word	Noun	Adjective	Verb	Adverb
sibilant	Yes	Yes	No	No
fricative	Yes	Yes	No	No

As adjectives, sibilant and fricative are synonyms defined as:

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

Other synonyms of sibilant include continuant, spirant, strident.

As nouns, fricative is a hypernym of sibilant; that is, fricative is a word with a broader meaning than sibilant:

sibilant: a consonant characterized by a hissing sound (like s or sh)
fricative: a continuant consonant produced by breath moving against a narrowing of the vocal tract

Other hypernyms of sibilant include fricative consonant, spirant.

sibilant (noun)	fricative (noun)
a consonant characterized by a hissing sound (like s or sh)	a continuant consonant produced by breath moving against a narrowing of the vocal tract

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