Origin: 1660–70; < Latinsībilant- (stem of sībilāns), present participle of sībilāre to hiss), equivalent to sībil(us) a hissing, whistling (of imitative orig.) + -ant--ant
1669, from L. sibilantem (nom. sibilans), prp. of sibilare "to hiss, whistle," possibly of imitative origin (cf. Gk. sizein "to hiss," Lett. sikt "to hiss," O.C.S. svistati "to hiss, whistle"). The noun meaning "speech sound having a hissing effect" is from 1788.