Dormitive is from Medieval Latin dormitivus, from Latin dormire ('to sleep'); famously cited in Molière's mock 'virtus dormitiva' of opium. The ancestry passes through Latin dormitivus, Latin dormire, and Proto-Indo-European *drem-. In present use as adjective and noun, it means "tending to induce sleep; soporific", keeping the historical formation close to the word's ordinary semantic work. Related words include dormant, dormitory, and dormitation. Its contrast set includes stimulant and stimulating, which clarifies the semantic boundary of the modern word.