Old English blædre (West Saxon), bledre (Anglian) "(urinary) bladder," also "blister, pimple," from Proto-Germanic *blaedron (cf. Old Norse blaðra, Old Saxon bladara, Old High German blattara, German Blatter, Dutch blaar), from PIE *bhle- "to blow" (see blast). Extended senses from early 13c. from animal bladders used for buoyancy, storage, etc.
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.
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.