ethylidene

from The Century Dictionary.

• noun A bivalent organic radical, CH₃CH ⟨. Sometimes called ethidene.

from the GNU version of the Collaborative International Dictionary of English.

• (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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry, especially in combination The divalent radical CH3-CH= formally obtained by removing two hydrogen atoms from the same carbon atom of ethane