Definition of "lights-out" []

• The time at night at which artificial lights are to be turned off, a curfew or bedtime. (noun)
• The prescribed bedtime for persons living in a boarding school or staying in a hospital. (noun)

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• "The plan was for the multinational formation to fly lights-out, but the different levels of training and experience began to tell."
• "This led to lights-out in winter mid-afternoon and thus the cycle repeated itself."
• "This party was not as raucous as the one for Sarge's first deployment, where lights-out came around 5 a.m."