chlorine (n.)

nonmetallic element, the name coined 1810 by English chemist Sir Humphry Davy from Latinized form of Greek khlōros "pale green" (from PIE root *ghel- (2) "to shine," with derivatives denoting "green" and "yellow") + chemical suffix -ine (2). Named for its color. Discovered 1774, but known at first as oxymuriatic acid gas, or dephlogisticated marine acid.