chlorine
/ˈklɔːriːn/noun
- the chemical element of atomic number 17, a toxic, irritant, pale green gas. (Symbol: Cl)氯（气）（符号：Cl）。
A member of the halogen group, chlorine occurs in nature mainly as sodium chloride in seawater and salt deposits. The gas was used as a poison gas in the First World War. Chlorine is added to water supplies as a disinfectant.
词源
early 19th cent.: named by Sir Humphrey Davy， from Greek khlōros 'green'+-INE4.