Lewis Short
(adjective) : infrēnis, e, and infrēnus, a, um (infraen-), 2. in - frenum
* Without a bridle, unbridled (poet. and post-class.).
* Lit.: infrenis equus,Verg. A. 10, 750: Numidae infreni,on unbridled horses,id. ib. 4, 41.
* Trop., untamed, unchecked: infreno volitare cursu, Col. poët. 10, 215: lingua infrenis,Gell. 1, 15, 17: infrenus manat de vulnere sanguis,Ser. Samm. 43, 804.
Charlton T. Lewis, Charles Short, A Latin Dictionary