The Collaborative International Dictionary of English v.0.48:

Bilimbi \Bi*lim"bi\, Bilimbing \Bi*lim"bing\, n. [Malay.]
   The berries of two East Indian species of Averrhoa, of the
   Oxalide[ae] or Sorrel family. They are very acid, and
   highly esteemed when preserved or pickled. The juice is used
   as a remedy for skin diseases. [Written also blimbi and
   blimbing.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

bilimbi
    n 1: East Indian evergreen tree bearing very acid fruit [syn:
         bilimbi, Averrhoa bilimbi]