Webster’s Revised Unabridged Dictionary · 1913
Olefiant
O·le′fi·ant (ō·lē′fĭ·ant; 277), a. [F. oléfiant, fr.L. oleum oil + -ficare (in comp.). Cf. -Fy.] (Chem.) Forming or producing an oil; specifically, designating a colorless gaseous hydrocarbon called ethylene. [Archaic]