Lewis Short
(adj.adv.) : somnĭālis, is, adj.somnium
* Dreambringing, an epithet of Hercules, Inscr. Fabr. p. 692, 130; Inscr. Rein. cl. 10, 4.— Hence, adv.: somnĭālĭter, in a dream (late Lat.), Fulg. Myth. 2, 17 dub.
Charlton T. Lewis, Charles Short, A Latin Dictionary