Source : Webster's Revised Unabridged Dictionary (1913)

Kangaroo \Kan"ga*roo"\, n. [Said to be the native name.]
   (Zo["o]l.)
   Any one of numerous species of jumping marsupials of the
   family {Macropodid[ae]}. They inhabit Australia, New Guinea,
   and adjacent islands, They have long and strong hind legs and
   a large tail, while the fore legs are comparatively short and
   feeble. The giant kangaroo ({Macropus major}) is the largest
   species, sometimes becoming twelve or fourteen feet in total
   length. The tree kangaroos, belonging to the genus
   {Dendrolagus}, live in trees; the rock kangaroos, of the
   genus {Petrogale}, inhabit rocky situations; and the brush
   kangaroos, of the genus {Halmaturus}, inhabit wooded
   districts. See {Wallaby}.

Source : WordNet®

kangaroo
     n : any of several herbivorous leaping marsupials of Australia
         and New Guinea having large powerful hind legs and a long
         thick tail