[1] : The Collaborative International Dictionary of English v.0.48

ethylene \eth"ylene\ e^th"i^l=en, 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.
   1913 webster

   ethylene series chem., the series of unsaturated
      hydrocarbons of which ethylene is the type, and
      represented by the general formula cnh2n.
      1913 webster
see also:
ethyl c2h4 olefiant gas ethene elayl bicarbureted hydrogen 
ethylene series cnh2n 

[2] : WordNet (r) 2.0

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
see also:
ethene 

Ethylene >> E Words
Ethylene, definition of term: Ethylene
ethylene_pag1.html

Ethylene Glycol >> E Words
Ethylene Glycol, definition of term: Ethylene Glycol
ethylene+glycol_pag1.html