ˈ ̷ ̷ˈ ̷ ̷ noun
( plural lights-out )
1. : a command or signal (as a bell or bugle call) for putting out lights
2. : a prescribed bedtime for persons living under discipline (as in a boarding school or army camp)
the only place where he could hide to study after lights-out — H.H.Martin
while away the hours before lights-out — English Digest