per-rārus, a, um, adj.,
very uncommon , very rare (as an adj. not in Cic.), Liv. 29, 38, 7: perrarum est, ut, etc., Plin. 31, 3, 23, § 38.—Adv.: perrārō , very seldom , very rarely : si quando id efficit, quod perraro potest. Cic. Rep. 2, 40, 67; id. Fin. 2, 16, 51; id. Rosc. Am. 18, 52: perraro haec alea fallit, Hor. S. 2, 5, 50.