The Collaborative International Dictionary of English v.0.48:

Elaeoptene \E`l[ae]*op"tene\, n. [Gr. ? olive oil, oil + ?
   winged, fleeting.] (Chem.)
   The more liquid or volatile portion of certain oily
   substance, as distinguished from stearoptene, the more solid
   parts. [Written also elaoptene.]
   [1913 Webster]