The word "somnific" refers to something that induces sleep or has sleep-inducing qualities. Its antonyms, on the other hand, are words that have the opposite meaning. Some possible antonyms for "somnific" could include stimulating, energizing, invigorating, revitalizing, or refreshing. These words suggest excitement, energy, and alertness, and are used to describe things that uplift and invigorate instead of causing drowsiness. For example, a cup of coffee or a brisk walk in the morning can be considered antonyms for "somnific," as they naturally perk us up and help us stay alert throughout the day.