Lewis Short
(adjective) : irrĕlĭgĭōsus (inr-), a, um, 2. inreligiosus
* Irreligious, impious (not anteAug.): irreligiosum ratus, sacerdotes pedibus ire, etc.,Liv. 5, 40 fin.: cujus (templi) dedicationem differre longius irreligiosum est,Plin. Ep. 4, 1, 5; 9, 35, 1: in Caesares,Tert. ad Nat. 1, 17.—Comp.: potest irreligiosius quidpiam existimari?Arn. 5, 185. —Sup.: factum irreligiosissimum,Tert. Or. 12. — Adv.: irrĕlĭgĭōsē, impiously: si qua irreligiose dixisset,Tac. A. 2, 50. — Comp., Arn. 1, 13; Tert. ad Nat. 1, 10.
Charlton T. Lewis, Charles Short, A Latin Dictionary