God brought them out of Egypt; he hath as it were the strength of an unicorn (Numbers 23:22, KJV)
Save me from the lion's mouth: for thou hast heard me from the horns of the unicorns (Psalm 22:21)
But my horn shalt thou exalt like the horn of an unicorn: I shall be anointed with fresh oil (Psalm 92:10)
Other than the Bible verses above, this believed mythical animal is found in Numbers 24:8, Deuteronomy 33:17, Job 39:9 - 12 (mentioned twice), Psalm 29:6 and Isaiah 34:7.
Unicorns were known to be strong and fierce (Numbers 23:22, 24:8, Job 39:11). They could not be trusted (Job 39:12) and were known for being untamable (Job 39:9). They were also quite agile (Psalm 29:6). They possessed at least one horn (Psalm 92:10) and quite possibly two (Deuteronomy 33:17, Psalm 22:21). In Numbers 23:22 and 24:8, they represented the power of God to deliver his people. In Isaiah 34, they symbolized the Eternal's judgment on the world for its sins.
"Come near, ye nations, to hear; and hearken, ye people: let the earth hear, and all that is therein; the world, and all things that come forth of it. For the indignation of the LORD is upon all nations . . .
"And the unicorns shall come down with them, and the bullocks with the bulls; and their land shall be soaked with blood, and their dust made fat with fatness. For it is the day of the Lord's vengeance, and the year of recompences for the controversy of Zion." (Isaiah 34:1 - 2, 7 - 8)
What could it be?
Biblical commentaries vary widely regarding what they think is the animal that is referenced. They state it could be an extinct wild bull called the auroch (Barnes), a rhino (Jamieson, Fausset and Brown), a wild buffalo or ox (Keil & Delitzsch), a wild goat (Wesley) or even an antelope (Bullinger's Companion Bible notes). Modern translations also vary in the way they translate the Hebrew word rame used for this animal. For example, in Isaiah 34:7, the word is translated 'oxen' in the NCV, 'wild oxen' in the NIV, NASB and others, and 'reems' in the YLT.
One medieval legend states that a unicorn's horn, if it touches the pool the animal is drinking from, renders the waters pure and sweet. According to the 1911 Encyclopedia Britannica, as late as 1789 the court ceremonial of France used instruments supposidly made from such horns for testing whether royal food contained poison (Volume 27, page 582). The use of this animal also found its way into the royal court of England.
"As a decoration of drinking cups it symbolized the ancient belief in the efficacy of the unicorn's horn against poison, which in England remained even in the time of Charles II (who was King of England, Scotland, and Ireland from 1660 to 1685 A.D.) . . ." (ibid. page 581 - 582)
In the Bible this beast represents the prophesied glory and power to come upon the descendants of Joseph (through his sons Ephraim and Manasseh - Deuteronomy 33:16 - 17). Many years after this prophecy was given ten of Israel's twelve tribes (which included Ephraim and Manasseh) were conquered by the Assyrians and taken captive. These tribes (commonly referred to as the lost tribes of Israel) migrated to several European countries after the Babylonians conquered Assyria in 612 B.C. Ephraim migrated to what is today England. It is more than a coincidence that this legendary animal, symbol of God's special blessing, found its way into the national symbol of the United Kingdom.
According to the 1913 Catholic Encyclopedia, the greatest variety of animals in art and architecture began in the thirteenth century. It is during this Gothic period that mythical beasts such as unicorns, dragons, griffons, cockatrices (basilisk), gargoyles, and others find expression, especially on churches. For example, the sculpted beast (pictured just above this paragraph) is found on the Cathedral of the Holy Cross and Saint Eulalia in Barcelona, Spain. The church building was started in 1298 and completed in 1420 A.D.