Unicorn (Lat. unum cornu, 'one horn'), a fabulous animal, mentioned by ancient Greek and Roman authors as a native of India, its body resembling that of a horse, exceeding swift, and having one straight horn a cubit and a half long on the forehead. Aristotle makes the oryx (an antelope) and the Indian ass one-horned. Although the descriptions of the unicorn given by the ancients are very unlike the Indian rhinoceros, yet probably that animal was the origin of them all. The word unicorn was unhappily used in translations of the Old Testament for the Hebrew rê'em. The Septuagint led the way in this, by using the Greek monokeros; and it has been supposed by many that the animal meant is a rhinoceros. But from Deut. xxxiii. 17 (where the Authorised Version has 'horns of unicorns') it is obvious the animal was two-horned; the revised translation has 'horns of the wild ox.' Elsewhere the alternative 'ox-antelope' is given in the margin of the new version. The spirally twisted unicorn's horn of heraldry is probably derived from the 'horn' of the Sea-unicorn or Narwhal (q.v.). The unicorn, as the sinister supporter of the royal arms, was adopted by James I. at the union of the crowns (cf. HERALDRY, Vol. V. pp. 668, 669).
See G. R. Brown, The Unicorn (1881); C. Gould, Mythical Monsters (1886).