The American Heritage® Dictionary of the English Language, 4th Edition
n. Any of several stocky burrowing Australian marsupials of the family Vombatidae, somewhat resembling a small bear and feeding mainly on grass, leaves, and roots.
n. Any of several herbivorous, burrowing marsupials, of the family Vombatidae, mainly found in southern and eastern Australia.
the GNU version of the Collaborative International Dictionary of English
n. Any one of three species of Australian burrowing marsupials of the genus Phascolomys, especially the common species (Phascolomys ursinus). They are nocturnal in their habits, and feed mostly on roots.
The Century Dictionary and Cyclopedia
n. An Australian marsupial mammal of the genus Phascolomys, as P. wombat or P. ursinus. See cut under Phascolomys.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
n. burrowing herbivorous Australian marsupials about the size of a badger
Word Usage
"Yes, "I was hit by a wombat" is in the passive voice (and properly so according to Pullum, if the wombat is a "newer and less established" element)."