The Collaborative International Dictionary of English v.0.48:

Quandong \Quan"dong\, n. (Bot.)
   The edible drupaceous fruit of an Australian tree (Fusanus
   acuminatus) of the Sandalwood family; -- called also
   quandang.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Fusanus acuminatus
    n 1: Australian tree with edible flesh and edible nutlike seed
         [syn: quandong, quandang, quandong tree, Eucarya
         acuminata, Fusanus acuminatus]