U'NICORN, n. L. unicornis unus, one, and cornu, horn.

1. an animal with one horn the monoceros. this name is often applied to the rhinoceros.
2. The sea unicorn is a fish of the whale kind, called narwal, remarkable for a horn growing out at his nose.
3. A fowl.

fossil unicorn, or fossil unicorn's horn, a substance used in medicine, a terrene crustaceous spar.