| 1. | Anatomy, Zoology.
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| 2. | Pathology. a vesicle, blister, cyst, etc., filled with fluid or air. |
| 3. | Botany. 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. |

| a distensible, muscular and membranous sac, in which the urine is retained until it is discharged from the body. |
A stretchable saclike structure in the body that holds fluids. The term is used most often to refer to the urinary bladder, which is part of the excretory system. Another kind of bladder is the gallbladder.
bladder blad·der (blād'ər)
n.
Any of various distensible membranous sacs, such as the urinary bladder, that serve as receptacles for fluid or gas.
A blister, pustule, or cyst filled with fluid or air; vesicle.
urinary bladder n.
A musculomembranous elastic receptacle in the anterior part of the pelvic cavity serving as the temporary storage place for urine.