ox vs wild ox

ox and wild ox both are nouns.

Word	Noun	Adjective	Verb	Adverb
ox	Yes	No	No	No
wild ox	Yes	No	No	No

As nouns, ox and wild ox are synonyms defined as:

ox and wild ox: any of various wild bovines especially of the genera Bos or closely related Bibos

ox (noun)	wild ox (noun)
any of various wild bovines especially of the genera Bos or closely related Bibos	any of various wild bovines especially of the genera Bos or closely related Bibos
an adult castrated bull of the genus Bos; especially Bos taurus