SIBILANTLY

Etymology

Adverb

sibilantly (comparative more sibilantly, superlative most sibilantly)

With a hissing or sibilant sound.

Source: Wiktionary

SIBILANT

Sib"i*lant, a. Etym: [L. sibilans, -antis, p. pr. of sibilare to hiss: cf. F. sibilant.]

Definition: Making a hissing sound; uttered with a hissing sound; hissing; as, s, z, sh, and zh, are sibilant elementary sounds.

– n.

Definition: A sibiliant letter.

Source: Webster’s Unabridged Dictionary 1913 Edition