Entry 1 sense Webster, 1913 Hypnagogic · Hyp·na·gog·ic · IPA /ˌhɪpnəˈɡɑd͡ʒɪk/ 01 a. Leading to sleep; -- applied to the illusions of one who is half asleep. 1. Leading to sleep; -- applied to the illusions of one who is half asleep.