unicorn

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A fabled creature symbolic of virginity and usually represented as a horse with a single straight spiraled horn projecting from its forehead.
• noun Heraldry A representation of this beast, having a horse's body, a stag's legs, a lion's tail, and a straight spiraled horn growing from its forehead, especially employed as a supporter for the Royal Arms of Great Britain or of Scotland.
• noun The constellation Monoceros.

from The Century Dictionary.

• noun A traditional or fabulous animal, with a single long horn, the monoceros of classic writers, commonly described as a native of India, but in terms not certainly applicable to any known animal.
• noun A mistranslation in the authorized version of the Bible (Deut. xxxiii. 17, and elsewhere) of the Hebrew word re'ēm.
• noun In heraldry, the representation of the fabulous animal used as a bearing.
• noun The unicorn-fish, unicorn-whale, sea-unicorn, or narwhal, whose enormously long single incisor tooth projects like a horn. See Monodon, monoceros, 3.
• noun The kamichi or horned screamer, Palamedea cornuta; the unicorn-bird. N. Grew. See cut under Palamedea.
• noun A kind of beetle having a single long horn; a unicorn-beetle. Various large beetles literally answer to this definition, being unicornous, with a large single prothoracic horn. See Dynastes, elephant-beetle, Hercules-beetle.
• noun In conchology, a unicorn-shell. See cut under Monoceros.
• noun A pair of horses with a third horse in front; also, the whole equipage.
• noun A Scottish gold coin issued by James III., James IV., and James V., having the figure of a unicorn on the obverse. Its standard weight was 58.89 grains troy, and it was current for 23 shillings Scotch.
• noun [capitalized] In astronomy, the constellation Monoceros.

from the GNU version of the Collaborative International Dictionary of English.

• noun A fabulous animal with one horn; the monoceros; -- often represented in heraldry as a supporter.
• noun A two-horned animal of some unknown kind, so called in the Authorized Version of the Scriptures.
• noun Any large beetle having a hornlike prominence on the head or prothorax.
• noun The larva of a unicorn moth.
• noun (Zoöl.) The kamichi; -- called also unicorn bird.
• noun (Mil.), obsolete A howitzer.
• noun (Med.) a substance formerly of great repute in medicine; -- named from having been supposed to be the bone or the horn of the unicorn.
• noun (Zoöl.) the narwhal.
• noun (Zoöl.) a notodontian moth (Cœlodasys unicornis) whose caterpillar has a prominent horn on its back; -- called also unicorn prominent.
• noun (Bot.) a name of two North American plants, the yellow-flowered colicroot (Aletris farinosa) and the blazing star (Chamælirium luteum). Both are used in medicine.
• noun (Zoöl.) 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A mythical beast traditionally represented as having the legs of a buck, the body of a horse, the tail of a lion with a single spiral horn on its head; a symbol of virginity.
• noun A heraldic representation of such a beast used as a charge or as a supporter; as in the arms of Great Britain and of Scotland.
• noun historical In various Bible translations, used to render the Latin unicornis or rhinoceros (representing Hebrew רְאֵם); a reem or wild ox.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun an imaginary creature represented as a white horse with a long horn growing from its forehead