Source : Webster's Revised Unabridged Dictionary (1913)

Oilseed \Oil"seed`\, n. (Bot.)
   (a) Seed from which oil is expressed, as the castor bean;
       also, the plant yielding such seed. See {Castor bean}.
   (b) A cruciferous herb ({Camelina sativa}).
   (c) The sesame.

Source : WordNet®

oilseed
     n : any of several seeds that yield oil