A unicorn is an imaginary creature that looks like a horse with a single, spiraling horn growing from its forehead. Stories about unicorns appear in myths and legends from around the world, often portraying them as rare, magical, and pure. In medieval tales, unicorns could only be approached by someone with a genuinely good heart, and their horns supposedly had healing powers.

Though unicorns never actually existed, ancient people might have created the legend after hearing travelers' descriptions of real animals like the rhinoceros or the narwhal (a whale with a long, twisted tusk). Some scholars think that profile views of certain antelopes, where both horns align and look like one, may have contributed to the myth.

Today, people use unicorn to describe anything extremely rare or nearly impossible to find. In business, a unicorn company is a startup worth over a billion dollars, which is exceptionally unusual. You might say you're searching for a unicorn if you're looking for something that combines qualities rarely found together, like a math tutor who's also hilarious and lives on your street. The word captures that sense of something so special and uncommon that finding it feels almost magical.