bladder: n. 1 a any of various membranous sacs in some animals, containing urine (urinary bladder), bile (gall-bladder), or air (swim-bladder). b this or part of it or a similar object prepared for various uses. 2 an inflated pericarp or vesicle in various plants. 3 anything inflated and hollow. [OE blódre f. Gmc]
