ethane UK /ˈiːθeɪn/US /ˈɛθeɪn/ noun2 •An aliphatic hydrocarbon, C₂H₆, gaseous at normal temperatures and pressures, being a constituent of natural gas. •The same compound, subjected to modification by replacing one or more of the hydrogen atoms with other radicals.chlorinated ethanes; halogenated ethanes formsethanes