Lewis Short
(adjective) : pervÄcus, a, um, pervico for pervinco
* Stubborn, obstinate (ante-class. collat. form of pervicax): pervico Ajax animo atque evocabili, Att. ap. Non. 487, 15 (Trag. Rel. p. 131 Rib.); Plaut. Fragm. ap. Non. 487, 15.
Charlton T. Lewis, Charles Short, A Latin Dictionary