Source : Webster's Revised Unabridged Dictionary (1913)

Pumpkin \Pump"kin\, n. [For older pompion, pompon, OF. pompon,
   L. pepo, peponis, Gr. ?, properly, cooked by the sun, ripe,
   mellow; -- so called because not eaten till ripe. Cf. {Cook},
   n.] (Bot.)
   A well-known trailing plant ({Cucurbita pepo}) and its fruit,
   -- used for cooking and for feeding stock; a pompion.

   {Pumpkin seed}.
   (a) The flattish oval seed of the pumpkin.
   (b) (Zo["o]l.) The common pondfish.

Source : WordNet®

pumpkin seed
     n : the edible seed of a pumpkin