OLEFIN Meaning of OLEFIN in English [ole.fin] n [ISV, fr. F (gaz) olefiant ethylene, fr. L oleum] (1860) 1: alkene 2: a synthetic fiber (as polypropylene) derived from an alkene -- ole.fin.ic adj Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012