kangaroo rat

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of various long-tailed rodents of the genus Dipodomys of arid areas of western North America, with long hind legs adapted for jumping.

Century Dictionary and Cyclopedia

1. n. An Australian marsupial of the family Macropodidœ, subfamily Potoroinœ or Hypsiprymninœ, and genus Potorous (or Hypsiprymnus), Æpiprymnus, or Bettongia; a bettong; a potoroo.
2. n. An American rodent of the family Saccomyidœ and subfamily Dipodomyinœ, as Dipodomys phillipsi or D. ordi. They resemble jerboas rather than kangaroos, and are common in the southwestern parts of the United States and Mexico. See Dipodomys.

Wiktionary

1. n. Any of many different species in genus Dipodomys, rodents that move about by hopping.

GNU Webster's 1913

1. n. (Zool.) A jumping rodent of the genus Dipodomys of the family Heteromyidae, which lives in arid regions of Mexico and the western U. S.
2. n. (Zool.) An Australian mammal of the genus Notomys.
3. n. (Zool.) a small ratlike Australian kangaroo of the genus Potorous, also called the potoroo.
4. n. (Zoöl.) the potoroo.

WordNet 3.0

1. n. any of various leaping rodents of desert regions of North America and Mexico; largest members of the family Heteromyidae
2. n. any of several rabbit-sized ratlike Australian kangaroos