Lewis Short
(adjective) : ef-frēnus, a, um (also effrenis mula, Plin. 8, 44, 69, § 171; Sen. de Ira, 3, 15, 2), ex-frenum
* Free from the bridle, unbridled (not ante Aug., and mostly poet. for effrenatus; cf. also: infrenus, infrenatus).
* Lit.: equus,Liv. 4, 33, 7.
* Trop., unbridled, unrestrained: gens,Verg. G. 3, 382: amor,Ov. M. 6, 465: juventa,Stat. Achill. 1, 277: profatu,id. Silv. 5, 3, 103.
Charlton T. Lewis, Charles Short, A Latin Dictionary