from where come the Unicorn ?

  In several passages (Numbers 23:22, 24:8; Deuteronomy 33:17; Job 39:9-10; Psalm 22:21, 29:6; Isaiah 34:7), the King James Version of the Bible mentions a unicorn. The original Hebrew is the word re’em which was translated monokeros in the Septuagint and unicornis in the Latin Vulgate. Later versions use the phrase “wild ox.” The original Hebrew word basically means “beast with a horn.” One possible interpretation is the rhinoceros. But since the Hebrew tow’apaha in Numbers 23:22 refers to more than one horn, it’s likely the translators of the Septuagint used creative license to infer a wild and powerful, but recognizable animal for their versions.

The re’em is believed to refer to aurochs or urus, large cattle which roamed Europe and Asia in ancient times. Aurochs stood over six feet tall and were the ancestors of domestic cattle. They became extinct in the 1600s. In the Bible, the “wild ox” usually refers to someone with great power. In Numbers 23:22 and 24:8, God compares His own strength to that of a wild ox. In Psalm 22:21, David imagines his enemies as wild oxen. The bull represented several different deities including Baal, Moloch, and the Egyptian Apis. The Israelites tried to adopt these beliefs when they made the golden calf.

Whether the re’em refers to a rhinocerous, or an auroch, or some other horned animal, the image is the same—that of an untamable, ferocious, powerful, wild animal. What we do know is that the Bible is not referring to the mythological “unicorn,” the horse-with-a-horn creature of fairy tales and fantasy literature. It is highly unlikely that the KJV translators believed in the mythological unicorn. Rather, they simply used the Latin term that described a “beast with a horn.”

 https://www.gotquestions.org/Bible-unicorn.html