lights out

noun

1. Chiefly Military.,  a signal, usually by drum or bugle, that all or certain camp or barracks lights are to be extinguished for the night.

2. bedtime.

lights out

noun

1. the time when those resident at an institution, such as soldiers in barracks or children at a boarding school, are expected to retire to bed

2. a fanfare or other signal indicating or signifying this

Word History and Origins

Origin of lights out¹

First recorded in 1865–70

Related Words

• collapse 
• departure 
• dissolution 
• downfall 
• extinction 
• failure 
• passing 
• termination