wild ox

“But it is impossible to determine what particular species of wild ox is signified probably some gigantic urus is intended.”

Smith's Bible Dictionary

“aurochsBos primigenia, the wild ox of Europe, extinct for a millennium.”

Simon & Schuster: Antony and Cleopatra

“Considering that the reem is spoken of as a two-horned animal of great strength and ferocity, that it was evidently well known and often seen by the Jews, that it is mentioned as an animal fit for sacrificial purposes, and that it is frequently associated with bulls and oxen we think there can be no doubt that, some species of wild ox is intended.”

Smith's Bible Dictionary