dīlūcŭlum, i, n. [diluceo],
daybreak, dawn (cf. crepusculum), Plaut. Am. 2, 2, 105; Cic. Rosc. Am. 7, 19; id. Att. 16, 13, a; cf. Macr. S. 1, 3 fin. ; Censor. 24; Vulg. Luc. 24, 1 et saep.—In plur., Fronto , Ep. ad Anton. 1, 5.
dīlūculum ī, n diluceo, daybreak, dawn . ...
An Elementary Latin Dictionary