ˈfäzˌjēn noun
( -s )
Etymology: phos- + -gene; from its being originally obtained by exposing equal volumes of chlorine and carbon monoxide to the sun's rays
: a colorless gaseous compound COCl 2 of unpleasant sour odor that condenses to a liquid at the temperature of ice, is usually made from carbon monoxide and chlorine in the presence of a catalyst, causes severe and often fatal edema of the lungs some hours after inhalation (as used as a poison gas in World War I), and is now used chiefly as an intermediate (as in the manufacture of organic isocyanates, polyurethanes, and carbonic esters) — called also carbon oxychloride, carbonyl chloride