Source : Webster's Revised Unabridged Dictionary (1913)

Cashew \Ca*shew"\ (k[.a]*sh[=oo]"), n. [F. acajou, for cajou,
   prob. from Malay k[=a]yu tree; cf. Pg. acaju, cf. {Acajou}.]
   (Bot.)
   A tree ({Anacardium occidentale}) of the same family which
   the sumac. It is native in tropical America, but is now
   naturalized in all tropical countries. Its fruit, a
   kidney-shaped nut, grows at the extremity of an edible,
   pear-shaped hypocarp, about three inches long.

   {Cashew nut}, the large, kidney-shaped fruit of the cashew,
      which is edible after the caustic oil has been expelled
      from the shell by roasting the nut.

Source : WordNet®

cashew
     n 1: tropical American evergreen tree bearing kidney-shaped nuts
          that are edible only when roasted [syn: {cashew tree}, {Anacardium
          occidentale}]
     2: kidney-shaped nut edible only when roasted [syn: {cashew nut}]