lights out

American  

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.

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lights out British  

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

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Etymology

Origin of lights out

First recorded in 1865–70

Example Sentences

"It means we can potentially design drugs that target the parasite's ARK1 specifically, turning the lights out on malaria without harming the patient."

From Science Daily • Mar. 5, 2026

Since then those stocks have been lights out, up 76% in 2023, 47.5% in 2024, and 19.3% last year, beating the market every year, according to FactSet.

From Barron's • Mar. 5, 2026

Maye was lights out for much of the season—there’s a reason he was in the MVP mix—and this will be the first mild weather game the Patriots have played in ages.

From The Wall Street Journal • Feb. 5, 2026

Sasaki, the team’s surprise playoff closer, had been lights out in the postseason, with just one of the 17 hitters he faced reaching base.

From Los Angeles Times • Oct. 14, 2025

And then Gwenforte lights out, running toward the queen, skimming over the shallow water like an angel.

From "The Inquisitor's Tale" by Adam Gidwitz

Related Words

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