green-colored stuff in plants, 1819, from French chlorophyle (1818), coined by French chemists Pierre-Joseph Pelletier (1788-1842) and Joseph Bienaimé Caventou (1795-1877) from chloro-, from Latinized form of Greek khlōros "pale green, greenish-yellow" (from PIE root *ghel- (2) "to shine," with derivatives denoting "green" and "yellow") + phyllon "a leaf" (from suffixed form of PIE root *bhel- (3) "to thrive, bloom").

"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.

Old English gielpan (West Saxon), gelpan (Anglian) "to boast, exult," from Proto-Germanic *gel- (source also of Old Saxon galpon, Old Norse gjalpa "to yelp," Old Norse gjalp "boasting," Old High German gelph "outcry"), from PIE root *ghel- (1) "to call, cry out." Meaning "utter a quick, sharp, bark or cry" is 1550s, probably from the noun. Related: Yelped; yelping.

white, solid substance present in body tissues, 1894, earlier cholesterin, from French cholestrine (Chevreul, 1827), from Latinized form of Greek khole "bile" (from PIE root *ghel- (2) "to shine," with derivatives denoting "green, yellow," and thus "bile, gall") + steros "solid, stiff" (from PIE root *ster- (1) "stiff"). So called because originally found in gallstones (Conradi, 1775). The name was changed to the modern form (with chemical suffix -ol, denoting an alcohol) after the compound was discovered to be a secondary alcohol.