The Collaborative International Dictionary of English v.0.48:

Elayl \E*la"yl\, n. [Gr. ? olive oil, oil + yl.] (Chem.)
   Olefiant gas or ethylene; -- so called by Berzelius from its
   forming an oil combining with chlorine. [Written also
   elayle.] See Ethylene.
   [1913 Webster]