Webster's Revised Unabridged Dictionary · 1913

Unicorn

Unicorn , noun

[Old English unicorne, French unicorne, Latin unicornis one-horned, having a single horn; unus one + cornu a horn; compare Latin unicornuus a unicorn. See One, and Horn.]

1.
A fabulous animal with one horn; the monoceros; -- often represented in heraldry as a supporter.
2.
A two-horned animal of some unknown kind, so called in the Authorized Version of the Scriptures.
Canst thou bind the unicorn with his band in the furrow? — Job xxxix. 10

The unicorn mentioned in the Scripture was probably the urus. See the Note under Reem.

3.
(a) (Zoology) Any large beetle having a hornlike prominence on the head or prothorax.
(b)
(Zoology) The larva of a unicorn moth.
4.
(Zoology) The kamichi; -- called also unicorn bird.
5.
(Military) A howitzer. [Obsolete]
Collocations (5)
Fossil unicorn or Fossil unicorn's horn (Medicine) , a substance formerly of great repute in medicine; -- named from having been supposed to be the bone or the horn of the unicorn.
Unicorn fish or Unicorn whale (Zoology) , the narwhal.
Unicorn moth (Zoology) , a notodontian moth (Coelodasys unicornis) whose caterpillar has a prominent horn on its back; -- called also unicorn prominent.
Unicorn root (Botany) , a name of two North American plants, the yellow-flowered colicroot (Aletris farinosa) and the blazing star (Chamaelirium luteum). Both are used in medicine.
Unicorn shell (Zoology) , any one of several species of marine gastropods having a prominent spine on the lip of the shell. Most of them belong to the genera Monoceros and Leucozonia.