any of a series of unsaturated open-chain hydrocarbons containing a double bond and having the general formula CH: these compounds are sometimes said to be in the ethylene or olefin series
See alkene in American Heritage Dictionary 4
(ălˈkēnˌ)
noun
Any of a series of unsaturated, open chain hydrocarbons with one or more carbon-carbon double bonds, having the general formula CnH2n.