Olefin

n. member of the alkene group (Chemistry)

In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond. The simplest alkenes, with only one double bond and no other functional groups, form a homologous series of hydrocarbons with the general formula CnH2n.The simplest alkene is ethylene (C2H4), which has the International Union of Pure and Applied Chemistry (IUPAC) name ethene. Alkenes are also called olefins (an archaic synonym, widely used in the petrochemical industry) or vinyl compounds.
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O·le·fin n. Any of a group of unsaturated open chain hydrocarbons possessing one or more double bonds, the simplest of which is ethylene. [more]Olefin - Community and Resources

Noun
1. any unsaturated aliphatic hydrocarbon
(synonym) alkene, olefine
(hypernym) aliphatic compound
(hyponym) ethylene, ethene

n. olefin, member of the alkene group, alkene (Chemistry)