2. (adj.) of or pertaining to sleep or drowsiness
3. (n.) something that causes sleepUSAGE EXAMPLE 1 :For a generation brought up on a diet of T20 cricket, a test match could prove to be positively soporific.USAGE EXAMPLE 2 :His lecture is titled "Meaning in American Politics," but it might have been better titled "Dreaming in American Politics," for it proves a powerful soporific.