Definition from Wiktionary, the free dictionary
zeedonk (plural zeedonks)
- A cross between a zebra and a donkey.
- 1997, Thomas Fensch, Of Sneetches and Whos and the Good Dr. Seuss 
- One might have imagined that it could only have been Dr. Seuss who had thought up and named the zedonk—the animal produced when a male zebra mates with a female donkey!
- 2003, Colin Bell, GCSE Applied Science Student Book 
- Suggest which animals are the parents of the cross breeds, zedonk and tiglion.
- 2004, Kevin O'Hara, Last of the Donkey Pilgrims 
- I could have told him about zedonks and zebrasses; donkey cures for whooping cough and gout, how an onager is a wild ass from Central Asia; that the Australian kookaburra is nicknamed “the laughing donkey”; [...]
- 1997, Thomas Fensch, Of Sneetches and Whos and the Good Dr. Seuss