Lewis & Short

fĕrōcĭo, īvi or ĭi, 4, v. n. [ferox], to be fierce, unruly, ungovernable; to rage, be furious: Ferocio, ἀγριαίνομαι, Gloss. Labb. (perh. only ante- and post-class.; for in Quint. 10, 3, 10, ferocientes equos is, acc. to the MSS., to be read efferentis se equos): ferocit apud Catonem ferociter agit, Paul. ex Fest. p. 92, 7 Müll.: si permulcti sonis mitioribus non immodice ferocirent, Gell. 1, 11, 2: oratio ferociens saeviensque, id. ib. § 15: in aliquam sectam, Tert. Apol. 5: ferociens, Amm. 14, 9, 9.