The Collaborative International Dictionary of English v.0.48:

Ethylate \Eth"y*late\ ([e^]th"[i^]l*[asl]t), v. t. [imp. & p. p.
   Ethylated; p. pr. & vb. n. Ethylating.] [From Ethyl.]
   (Chem.)
   To treat in such a way as to cause the introduction of one or
   more ethyl groups, C2H5-; as, to ethylate alcohol.
   [Webster 1913 Suppl.]