Source : Webster's Revised Unabridged Dictionary (1913)

Propylene \Pro"pyl*ene\, n. [Cf. F. propyl[`e]ne.] (Chem.)
   A colorless gaseous hydrocarbon ({C3H6}) of the ethylene
   series, having a garlic odor. It occurs in coal gas, and is
   produced artificially in various ways. Called also {propene}.

Source : WordNet®

propylene
     n : a flammable gas obtained by cracking petroleum; used in
         organic synthesis [syn: {propene}]