Source : Webster's Revised Unabridged Dictionary (1913)

Ethyl \Eth"yl\, n. [Ether + -yl.] (Chem.)
   A monatomic, hydrocarbon radical, {C2H5} of the paraffin
   series, forming the essential radical of ethane, and of
   common alcohol and ether.

   {Ethyl aldehyde}. (Chem.) See {Aldehyde}.

Source : WordNet®

ethyl
     n : the univalent hydrocarbon radical C2H5 derived from ethane
         by the removal of one hydrogen atom [syn: {ethyl group},
         {ethyl radical}]