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stay up - Wiktionary, the free dictionary

From Wiktionary, the free dictionary

stay up (third-person singular simple present stays up, present participle staying up, simple past and past participle stayed up)

  1. Used other than figuratively or idiomatically: see stay,‎ up.

    These trousers are too big around the waist. They won't stay up.

  2. (intransitive) To remain awake; to not go to bed.

    My plane leaves at 6:00 in the morning, so I plan to stay up until then and sleep on the plane.

    She stayed up past her bedtime.

  3. (intransitive, euphemistic) To maintain an erection.

    He told his lover he has a problem staying up.

remain awake

maintain an erection