Source : Webster's Revised Unabridged Dictionary (1913)

Mangosteen \Man"go*steen\, Mangostan \Man"go*stan\, n. [Malay
   mangusta, mangis.] (Bot.)
   A tree of the East Indies of the genus {Garcinia} ({G.
   Mangostana}). The tree grows to the height of eighteen feet,
   and bears fruit also called mangosteen, of the size of a
   small apple, the pulp of which is very delicious food.

Source : WordNet®

mangosteen
     n 1: East Indian tree with thick leathery leaves and edible fruit
          [syn: {mangosteen tree}, {Garcinia mangostana}]
     2: two- to three-inch tropical fruit with juicy flesh
        suggestive of both peaches and pineapples