somnificus

A New Latin Dictionary by Charlton T. Lewis Ph.D. and Charles Short, LL. D.

somnĭfĭcus, a, um, adj. [somnus-facio],

causing sleep , narcotic (Plinian): crater, Mart. Cap. 1, § 82: medicamentum, Plin. 37, 10, 57, § 158: vis aspidum, id. 24, 4, 17, § 63.