Unicorn definition
Mythological animal resembling a white horse with a single horn on its forehead. The unicorn was depicted in Mesopotamian art and was referred to in the ancient myths of India and China. Its earliest description in Greek literature dates from c. 400 BC and probably refers to the Indian rhinoceros. The unicorn was believed to be fierce and difficult to capture, but if a virgin were brought before it, it would lay its head in the virgin's lap. Its horn was thought to offer protection against poison. Medieval writers associated the unicorn with Jesus, and the hunt for the unicorn was often represented in medieval art. Medieval knowledge of the fabulous beast stemmed from biblical and ancient sources, and the creature was variously represented as a kind of wild ass, goat, or horse. By AD 200, Tertullian had called the unicorn a small fierce kidlike animal, and a symbol of Christ. Ambrose, Jerome and Basil agreed.

The predecessor of the medieval bestiary, compiled in Late Antiquity and known as Physiologus, popularized an elaborate allegory in which a unicorn, trapped by a maiden (representing the Virgin Mary) stood for the Incarnation. As soon as the unicorn sees her it lays its head on her lap and falls asleep. This became a basic emblematic tag that underlies medieval notions of the unicorn, justifying its appearance in every form of religious art. The unicorn also figured in courtly terms: for some thirteenth-century French authors such as Thibaut of Champagne and Richard of Fournival, the lover is attracted to his lady as the unicorn is to the virgin. This courtly version of salvation provided an alternative to God's love and was assailed as heretical [citation needed]. With the rise of humanism, the unicorn also acquired more orthodox secular meanings, emblematic of chaste love and faithful marriage. It plays this role in Petrarch's Triumph of Chastity. The royal throne of Denmark was made of "unicorn horns". The same material was used for ceremonial cups because the unicorn's horn continued to be believed to neutralize poison, following classical authors. Though the modern popular image of the unicorn is sometimes that of a horse differing only in the horn, the traditional unicorn has a billy-goat beard, a lion's tail, and cloven hooves, which distinguish him from a horse.[1] Marianna Mayer has observed (The Unicorn and the Lake), "The unicorn is the only fabulous beast that does not seem to have been conceived out of human fears. In even the earliest references he is fierce yet good, selfless yet solitary, but always mysteriously beautiful. He could be captured only by unfair means, and his single horn was said to neutralize poison. It has also been rumored that the unicorn's horn was originally a phallic symbol. This may be related to the medieval notion that grinding the horn and diluting the powder in water created a powerful aphrodisiac.

Modern fantasy fiction tends to perpetuate the medieval notion of a unicorn as a beast with magical qualities or powers. Unicorns notably appear in:
Peter S. Beagle's The Last Unicorn and The Unicorn Sonata
Michael Bishop's Unicorn Mountain
Terry Brooks's The Black Unicorn
Bruce Coville's A Glory of Unicorns, Into the Land of the Unicorns and Song of the Wanderer
Neil Gaiman's Stardust
Michael Green's De Historia Et Veritate Unicornis (On the History and Truth of the Unicorn)
David Lee Jones's Unicorn Highway
John Lee's Unicorn Quest series
Tanith Lee's The Black Unicorn, The Gold Unicorn and The Red Unicorn
C. S. Lewis's The Last Battle (part of the Chronicles of Narnia)
Marianne Moore has a poem entitled Sea Unicorns and Land Unicorns

Harry Potter Glossary: Unicorns are one horned white horse like animals that live in the Forbidden Forest. Their blood has magical properties that can keep a person alive, but at a cost.
Forbidden Forest: The Forbidden Forest is the forest that surrounds Hogwarts. It is the home to many mythical and dangerous creatures.
Hogwarts Academy of Witchcraft and Wizardry: Wizarding school that young witches or wizards enter after they turn 11. It was founded by Godric Gryffindor, Salazar Slytherin, Helga Hufflepuff and Rowena Ravenclaw, all of whom have houses named after them. Hogwarts School of Witchcraft and Wizardry is a fictional school of magic that is the main setting of the Harry Potter series.