The Collaborative International Dictionary of English v.0.48:

Propane \Pro"pane\, n. [Propyl + methane.] (Chem.)
   A heavy gaseous hydrocarbon, C3H8, of the paraffin series,
   occurring naturally dissolved in crude petroleum, and also
   made artificially; -- called also propyl hydride.
   [1913 Webster]

WordNet (r) 3.0 (2006):

propane
    n 1: colorless gas found in natural gas and petroleum; used as a
         fuel