a. [ Gr. fw^s light + the root of gi`gnesqai to be born: cf. F. phosgène. ] (Old Chem.) Producing, or produced by, the action of light; -- used specifically to designate a gas also called carbonyl chloride. See phosgene, n., and Carbonyl. [ 1913 Webster + PJC ]
n. (Chem.) A reactive chemical substance (COCl2), also called carbonyl choride, used in synthesis of numerous substances. In the First World War it was also used as a poisonous gas in combat. [ PJC ]