Source : Webster's Revised Unabridged Dictionary (1913)

Ethylene \Eth"yl*ene\ (-[=e]n), n. [From {Ethyl}.] (Chem.)
   A colorless, gaseous hydrocarbon, {C2H4}, forming an
   important ingredient of illuminating gas, and also obtained
   by the action of concentrated sulphuric acid in alcohol. It
   is an unsaturated compound and combines directly with
   chlorine and bromine to form oily liquids (Dutch liquid), --
   hence called {olefiant gas}. Called also {ethene}, {elayl},
   and formerly, {bicarbureted hydrogen}.

Source : WordNet®

ethylene
     n : a flammable colorless gaseous alkene; obtained from
         petroleum and natural gas and used in manufacturing many
         other chemicals; sometimes used as an anesthetic [syn: {ethene}]