<p><strong>Noun</strong></p><ul><li>Anatomy, Zoology: a membranous sac or organ serving as a receptacle for a fluid or air.</li><li>Urinary bladder.</li><li>Pathology: a vesicle, blister, cyst, etc., filled with fluid or air.</li><li>Botany: an air-filled sac or float, as in certain seaweeds.</li><li>Something resembling a bladder, as the inflatable lining of a football or basketball.</li><li>An air-filled sac, usually made to resemble a club, used for beatings in low comedy, vaudeville, or the like.</li></ul>