The Collaborative International Dictionary of English v.0.48:

Sebesten \Se*bes"ten\ (s[-e]*b[e^]s"t[e^]n), n. [Ar. sebest[=a]n
   the tree: cf. Sp. sebesten.] (Bot.)
   The mucilaginous drupaceous fruit of two East Indian trees
   (Cordia Myxa, and Cordia latifolia), sometimes used
   medicinally in pectoral diseases.
   [1913 Webster]

   Note: In the West Indies the name is given to the similar
         fruit of Cordia Sebestana.
         [1913 Webster]