chlor·ine [chlorinechlorines] BrE [ˈklɔːriːn] NAmE [ˈklɔːriːn] noun uncountable (symb. Cl) a chemical element. Chlorine is a poisonous greenish gas with a strong smell. It is often used in swimming pools to keep the water clean.
Word Origin: early 19th cent.: named by Sir Humphrey Davy, from Greek khlōros ‘green’ -ine.