either of two alkanes ( and ) having the same formula, CH, but different structures and used esp. as a fuel
See butane in American Heritage Dictionary 4
(byo͞oˈtānˌ)
noun
Either of two isomers of a gaseous hydrocarbon, C4H10, produced synthetically from petroleum and used as a household fuel, refrigerant, and aerosol propellant and in the manufacture of synthetic rubber.