olefiant gas

[oh-luh-fahy-uh nt, oh-lee-fee-, oh-lef-ee-] /ˌoʊ ləˈfaɪ ənt, oʊˈli fi-, oʊˈlɛf i-/
noun
1.
ethylene (def 2).
Origin
1800-10; part translation of French gaz oléfiant, equivalent to olé- (< Latin oleum oil) + -fiant, present participle of -fier -fy; see -ant