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1 an insomniac.
2 a medication or other substance that prevents sleep.
3 causing wakefulness.
agrypnoticadjective An obsolete term referring to insomnia (or wakefulness); insomniac; awake.
noun An obsolete term for an agent which causes insomnia (or wakefulness).
agrypnotic(ă″grip-not′ik) [Gr. agrypnos, sleepless]
1. Afflicted with insomnia.
2. Causing wakefulness.