In a Word: Unicorn vs. Rhinoceros

Senior managing editor and logophile Andy Hollandbeck reveals the sometimes surprising roots of common English words and phrases. Remember: Etymology tells us where a word comes from, but not what it means today.

Around 400 B.C. lived a man named Ctesias of Cnidus. He was well-known in his day for two things: First, he was a Greek physician in the employ the king of Persia, but that part of his life doesn’t figure in to this word history. He was also a historian with a great interest in Persia and India. In some of his writings about Indian fauna around 398 B.C., Ctesias described “wild asses as large as horses, some being even larger. Their head is of a dark red color, their eyes blue, and the rest of their body white. They have a horn on their forehead, a cubit in length.” He also noted how people drank from these horns to protect themselves from poison and to prevent convulsions.

Powerful, almost magical stuff.

But here’s the rub: Ctesias never made it to India himself. What he wrote was his interpretation of someone else’s description of an animal that was most likely what we call today an Indian rhinoceros. But you can understand how, drawing on the characteristics of animals he was more personally acquainted with, his mind’s eye might conjure something more like the unicorn we know today.

So it was with the people who read his work, too, and thus with Ctesias’s writings we see the early stages of what by Medieval times would become the elusive, magical, mythical, snow-white, horse-like unicorn.

Ctesias didn’t call it a unicorn, though. The animal was called, in Greek, monokeros — a combination of mono “one” and keras “horn.”

And then a weird thing happened to spread knowledge of this mythical beast throughout Western culture. When scholars were translating Jewish texts into Greek in the third century B.C., they came across an animal called a re’em. They knew it was some type of large, powerful beast, but one that they weren’t familiar with. (They would have known the Hebrew word for, say, “elephant” or “bear.”) In the absence of a better option, they decided that descriptions of the re’em were similar enough to Ctesius’s description of the monokeros that it would be an okay translation.

A few centuries down the road, these Jewish texts became part of the Christian Old Testament, and when the Church translated them to Latin, monokeros was translated literally into unicornus — again, “one horn.” This became the English unicorn.

Bible scholars today believe that the re’em probably refers to the aurochs, a now-extinct type of wild ox. In modern English Bibles, the unicorns have been replaced with wild oxen  — but that shift didn’t come until much, much later. When the King James Bible was first published in 1611, the Old Testament included several mentions of unicorns, in Numbers 23 and 24, Job 39, Psalms 22, 29, and 92, and this rather chilling mention from Isaiah 34:6-7:

The sword of the Lord is filled with blood, it is made fat with fatness, and with the blood of lambs and goats, with the fat of the kidneys of rams: for the Lord hath a sacrifice in Bozrah, and a great slaughter in the land of Idumea [Edom]. 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.

Through these English and Latin Bible translations, unicorns reached all of Christendom.

But back to the rhinoceros: Two of the three extant species of rhinos native to Asia (like the Indian rhino in the image at the top of this post) have a single horn, as described by Ctesias. But the two species of African rhinos actually have two horns, one in front of the other. Monokeros therefore wouldn’t be an accurate description of them. So these animals were called instead rhinokeros in Greek, which became the English rhinoceros, from the Greek rhinos “nose”; rhinoceros, therefore, literally means “nose-horned.”

And eventually, of course, that name would apply to the whole rhinoceros family.