a signal, as of a drum or bugle, sounded early in the morning to awaken military personnel and to alert them for assembly.
2.
a signal to arise.
Origin: 1635–45; < French réveillez, plural imperative of réveiller to awaken, equivalent to r(e)-re- + éveiller,Old French esveillier ≪ Latin ēvigilāre to watch, be vigilant (ē-e- + vigilāre to watch; see vigil)
1644, from Fr. réveillez (vous) "awaken!" imperative plural of réveiller "to awaken, to wake up," from M.Fr. re- "again" + eveiller "to rouse," from V.L. *exvigilare, from L. ex- "out" + vigilare "be awake, keep watch" (see vigil).