phosgene

phosgene
    n 1: a colorless poisonous gas that smells like new-mown hay;
         used in chemical warfare
    

Phosgene \Phos"gene\, a. [Gr. fw^s light + the root of
   gi`gnesqai to be born: cf. F. phosg[`e]ne.] (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]
    

phosgene \phos"gene\ (f[o^]s"j[=e]n or f[o^]z"j[=e]n), 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]
    

Carbonyl \Car"bon*yl\, n. [Carbon + -yl.] (Chem.)
   The radical ({=CO}), occuring, always combined, in many
   compounds, as the aldehydes, the ketones, urea, carbonyl
   chloride, etc.
   [1913 Webster]

   Note: Though denoted by a formula identical with that of
         carbon monoxide, it is chemically distinct, as carbon
         seems to be divalent in carbon monoxide, but
         tetravalent in carbonyl compounds.
         [1913 Webster]

   {Carbonyl chloride} (Chem.), a colorless gas, {COCl2}, of
      offensive odor, and easily condensable to liquid. It is
      formed from chlorine and carbon monoxide, under the
      influence of light, and hence has been called {phosgene},
      or {phosgene gas}; -- called also {carbon oxychloride}. It
      is used in chemical synthesis, and was also used as a
      poison gas in World War I.
      [1913 Webster +PJC]