—v.t. 1. to bind or oblige morally or legally: to obligate oneself to purchase a building. 2. to pledge, commit, or bind (funds, property, etc.) to meet an obligation.
—adj. 1. morally or legally bound; obliged; constrained.
2. necessary; essential.
3. Biol.restricted to a particular condition of life, as certain organisms that can survive only in the absence of oxygen: obligate anaerobe (opposed to facultative).