Lewis & Short

sībĭlo (collat. form sīfĭlo, Non. 531, 2), āre, v. n. and a. [sibilus] (class. but rare).

  1. I. Neutr., to hiss, to whistle: imitationis hoc modo, ut majores rudere et vagire et mugire et murmurare et sibilare appellaverunt, Auct. Her. 4, 31, 42: (serpens) sibilat ore, * Verg. A. 11, 754; so of a serpent, Prop. 4 (5), 7, 54; Ov M. 4, 588.
    Of gossips: contemplent, conspiciant omnes, nutent, nictent, sibilent, * Plaut. Merc. 2, 3, 72.
    Of things: illud (ferrum igne rubens) Stridet et in trepidā submersum sibilat undā, Ov. M. 12, 279: stridor rudentum sibilat, whistles, Sil. 17, 258; cf. aura, Luc. 2, 698: tempestas, Quint. Decl. 12, 16: horrendo fragore sibilantibus armis, Amm. 31, 12, 12.
  2. II. Act., to hiss, i. e. to hiss at, hiss down a person, Cic. Att. 2, 19, 2: populus me sibilat; at mihi plaudo Ipse domi, Hor. S. 1, 1, 66.