Olefiant \O*le"fi*ant\, a. [F. ol['e]fiant, fr.L. oleum oil + -ficare (in comp.). Cf. -Fy.]

(Chem.) Forming or producing an oil; specifically, designating a colorless gaseous hydrocarbon called ethylene (olefiant gas). [Archaic] [1913 Webster] olefin

Source: The Collaborative International Dictionary of English v.0.48
 

Olefiant \O*le"fi*ant\, a. [F. ol['e]fiant, fr.L. oleum oil + -ficare (in comp.). Cf. -Fy.]

(Chem.) Forming or producing an oil; specifically, designating a colorless gaseous hydrocarbon called ethylene. [Archaic]

Source: Webster's Revised Unabridged Dictionary (1913)