adj, noun ·Rare ·Advanced level

Definitions

Noun

1. 1
   The time at night at which artificial lights are to be turned off, a curfew or bedtime. uncountable
2. 2
   (military) signal to turn the lights out wordnet
3. 3
   The prescribed bedtime for persons living in a boarding school or staying in a hospital. uncountable

   "We were all expected to be in bed by lights-out."

4. 4
   a prescribed bedtime wordnet
5. 5
   Something hopeless, over; unconsciousness. euphemistic, idiomatic, uncountable

   "It's gonna be lights out for you, pal!"

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6. 6
   A decisive play. idiomatic, uncountable

   "No one could really stop him in the second half and he was lights-out in OHL playoffs."

Adjective

1. 1
   Done or performed in the dark because of a fully automated working environment. Often describes night shift or third shift work. not-comparable

   "lights-out manufacturing"

Synonyms

All synonyms

taps

Example

More examples

"We were all expected to be in bed by lights-out."

Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.