gall-bladder (n.)

"bile, liver secretion," Old English galla (Anglian), gealla (West Saxon) "gall, bile," from Proto-Germanic *gallon "bile" (source also of Old Norse gall "gall, bile; sour drink," Old Saxon galle, Old High German galla, German Galle), from PIE root *ghel- (2) "to shine," with derivatives denoting "green, yellow," and thus "bile, gall." Informal sense of "impudence, boldness" first recorded American English 1882; but meaning "embittered spirit, rancor" is from c. 1200, from the old medicine theory of humors.

Middle English bladdre, from Old English blædre (West Saxon), bledre (Anglian) "urinary bladder," also "blister, pimple," from Proto-Germanic *blodram "something inflated" (source also of Old Norse blaðra, Old Saxon bladara, Old High German blattara, German Blatter, Dutch blaar), from PIE root *bhle- "to blow." The extended senses date from early 13c., from animal bladders being used for buoyancy, storage, etc.