The Collaborative International Dictionary of English v.0.48:

Pinon \Pi[~n]"on\, n. [Sp. pi[~n]on.] (Bot.)
      (a) The edible seed of several species of pine; also, the
          tree producing such seeds, as Pinus Pinea of
          Southern Europe, and Pinus Parryana, cembroides,
          edulis, and monophylla, the nut pines of Western
          North America.
      (b) See Monkey's puzzle. [Written also pignon.]
          [1913 Webster]

WordNet (r) 3.0 (2006):

pinon
    n 1: any of several low-growing pines of western North America
         [syn: pinon, pinyon]