<p><strong>Noun</strong></p><ul><li>a plant, <em>Allium cepa</em>, of the amaryllis family, having an edible, succulent, pungent bulb</li><li>any of certain similar plants</li><li>the bulb of the onion plant</li><li>the flavor or odor of this bulb</li><li>Slang: a person; "He's a tough onion"</li></ul><p><strong>Adjective</strong></p><ul><li>containing or cooked with onions: onion soup</li><li>of, relating to, or resembling an onion</li></ul>