Re'em also called Reëm (Hebrew: רֶאֵם), is the Hebrew word for "aurochs" and is mentioned nine times in the Hebrew Bible (Job 39:9-10, Deuteronomy 33:17, Numbers 23:22 and 24:8; Psalms 22:21, 29:6 and 92:10; and Isaiah 34:7) it is translated as "bullocks" or "wild-ox" in most Jewish translations and erroneously as "unicorn" in the Authorized King James Version. It was first identified in modern times with the aurochs by Johann Ulrich Duerst who discovered it was based on the Akkadian cognate rimu, meaning Bos primigenius, the aurochs, progenitor of cattle. Johann Ulrich Duerst published this in Die Rinder von Babylonian, Assyrien und Ägypten (Berlin, 1899:7-8), and was generally accepted, as by Salo Jonas, "Cattle Raising in Palestine" Agricultural History 26.3 (July 1952), pp. 93-104, as it is today even among non-scholarly Christians: "Was the Assyrian 'Rimu' mistranslated as unicorn?" Some Creationists believe it to be a triceratops: "The Sanilac Petroglyphs, Paleo-cryptozoology, and Controversy" Revolution against Evolution

The King James Version of Job followed the Septuagint and Jerome Vulgate in its translation unicorn:

"Will the unicorn be willing to serve thee, or abide by thy crib? Canst thou bind the unicorn with band in the furrow? or will he harrow the valleys after thee? Wilt thou trust him, because his strength is great? or wilt thou leave thy labour to him? Wilt thou believe him, that he will bring home thy seed, and gather it into thy barn?"Book of Job 39:9–12.

Re'em is translated as "wild ox" in the New American Standard Bible. Re'em is also speculated to refer to the Arabian Oryx.

In the Jewish folklore, the Re'em was so large that Noah had to strap it on the side of the Ark, and King David, while still a shepherd, mistook its horn for a mountain and climbed it, then the Re'em got up and frightened David. He prayed to God to save him, so a lion passed in front of the Re'em, and as the Re'em bowed down to the king of beasts, David climbed off, but was threatened by the lion. He prayed again and an animal passed by so the lion could chase it, and David left unharmed.

Taken from the Glasgow Argus newspaper of 7 December 1835: Our visitor is of ancient lineage, though we are by no means certain that it can be traced quite so far back as his flatterers have attempted to do. Some have represented him as the lineal descendant of the Reem, of whom mention is made in the Books of Number and Deuteronomy, in the Psalms, in Job, and in Isaiah. The genealogy is not very clearly made out. In the kindred dialect of the Arabic, Rem denotes an antelope. Of course this does not prove that the Hebrew Reem was an antelope; for only from scientific zoologists can we expect critical accuracy in the matter of names, and we know well the carelessness with which colonists apply the names of the beasts and birds of their fatherland to those which they find in their new domicile. On the other hand, the text of the Septuagint favours the identity of the Reem with the rhinoceros, by translating it monoceros. The Ethiopic translation of the Scriptures renders it Arwe Harish, the names of the rhinoceros; this, however, is of little consequence, as it seems now to be admitted that that translation was made from the Septuagint. This latter, however, was effected before the birth of our Saviour, by Jews resident in Egypt, at a time when the rhinoceros was frequently exhibited there as a part of the royal pomp of the Ptolemies.

The account given of the form and habits of the Reem, in the sacred books, are far too slender to add anything satisfactory to this vague guess-work. In one passage it seems implied that the Reem was abundant on the north-east frontier of the Israelites, from Anti-Lebanon towards Bozrah. In “Job” the strength of the animal, and the impossibility of making it available in agricultural labour, is hinted at. The elevation of the horn is always the most prominent, if indeed not the only feature alluded to. In the twenty-second Psalm, it would almost seem, from the juxtaposition, that the “shooting of the lip” was the image which raised up the Reem in the poet’s imagination. Altogether, these combined hints produce a very faint and indistinct picture of the animal.