亞乙基
Ethylidene \E*thyl"i*dene\ (Chem.) An unsymmetrical, divalent, hydrocarbon radical, {C2H4} metameric with ethylene but written thus, {CH3.CH} to distinguish it from the symmetrical ethylene, {CH2.CH2}. Its compounds are derived from aldehyde. Formerly called also {ethidene}.