Vinyl \Vi"nyl\, n. [L. vinum wine + -yl.]

(Chem.) The hypothetical radical C2H3, regarded as the characteristic residue of ethylene and that related series of unsaturated hydrocarbons with which the allyl compounds are homologous.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Ethenyl \Eth"e*nyl\, n. [Ethene + -yl.]

(Chem.)
   (a) A trivalent hydrocarbon radical, CH3.C.
   (b) A univalent hydrocarbon radical of the ethylene series, CH2:CH; -- called also vinyl. See Vinyl.

Source: Webster's Revised Unabridged Dictionary (1913)