Lewis Short
(adjective) : portentÄfÄcus, a, um, portentum-facio
* Marvellous, monstrous, unnatural, extraordinary (poet. and in post-class. prose): venena,Ov. M. 14, 55 Jahn (al. portentifera): figurae animalium,Lact. 2, 13, 11: opera,id. 4, 13, 15.
Charlton T. Lewis, Charles Short, A Latin Dictionary