Bible Dictionaries
Unicorn

People's Dictionary of the Bible

Unicorn, reêm, or high. Numbers 23:22, A. V., but R. V. reads "wild ox." The word occurs seven times in the Old Testament. That fabulous creature the unicorn certainly is not meant by the Hebrew reêm. Critics are agreed that the passages mentioning it, correctly understood, require an animal with two horns. This animal was distinguished for his ferocity, Isaiah 34:7, strength, Numbers 23:22; Numbers 24:8, agility, Psalms 29:6, wildness, Job 39:9, as well as for being horned, and destroying with his horns. Deuteronomy 33:17; Psalms 22:21. For various reasons this animal could not have been the rhinoceros. Probably it was the now extinct aurochs (Bos primigenius), a long-horned and powerful ox, which existed in the forests of Europe nearly, or quite, until the Middle Ages. An allied species of great size and strength is known to have existed in Palestine, as the bison (Bison bonasus), and some or these, now called aurochs, are still found in the forests of Lithuania.

Bibliography Information
Rice, Edwin Wilbur, DD. Entry for 'Unicorn'. People's Dictionary of the Bible. https://www.studylight.org/​dictionaries/​eng/​rpd/​u/unicorn.html. 1893.