Pronunciation: (blad'ur),[key] —n. 1. Anat.,Zool. a. a membranous sac or organ serving as a receptacle for a fluid or air.
b. See urinary bladder. 2. Pathol.a vesicle, blister, cyst, etc., filled with fluid or air.
3. Bot.an air-filled sac or float, as in certain seaweeds.
4. something resembling a bladder, as the inflatable lining of a football or basketball.
5. an air-filled sac, usually made to resemble a club, used for beatings in low comedy, vaudeville, or the like.