<p><strong>Verb</strong></p><ul><li>(used with object) to bind or oblige morally or legally: to obligate oneself to purchase a building.</li><li>To pledge, commit, or bind (funds, property, etc.) to meet an obligation.</li></ul><p><strong>Adjective</strong></p><ul><li>Morally or legally bound; obliged; constrained.</li><li>Necessary; essential.</li><li>Biology: restricted to a particular condition of life, as certain organisms that can survive only in the absence of oxygen (facultative): obligate anaerobe.</li></ul>