ETYM French réveil, from réveiller to awake; pref. re- re- + pref. es- (Latin ex) + veiller to awake, watch, Latin vigilare to watch. The English form was prob. taken by mistake from the French imper. réveillez,2d pers. pl. Related to Vigil.
1. A signal to get up in the morning; in the military it is a bugle call at sunrise.
2. (Military) Signal to wake up; SYN. wake-up signal.; signal to waken soldiers, sounded on drum or bugle.