ox 
(ŏks)
(ŏks)n. pl. ox·en (ŏksən)
1. An adult castrated bull of the genus Bos, especially B. taurus, used chiefly as a draft animal.
2. A bovine mammal, especially one that has been domesticated.
[Middle English, from Old English oxa; see uks-en- in the Appendix of Indo-European roots.]