horn / hôrn/ • n. 1. a hard permanent outgrowth, often curved and pointed, found in pairs on the heads of cattle, sheep, goats, giraffes, etc., and consisting of a core of bone encased in keratinized skin. ∎  a woolly keratinized outgrowth, occurring singly or one behind another, on the snout of a rhinoceros. ∎  a deer's antler. ∎  a hornlike projection on the head of another animal, e.g., a snail's tentacle or the tuft of a horned owl. ∎  (horns) archaic a pair of horns as an emblem of a cuckold. 2. the substance of which horns are composed: powdered rhino horn. ∎  a receptacle or instrument made of horn, such as a drinking container or powder flask. 3. a thing resembling or compared to a horn in shape. ∎  a horn-shaped projection. ∎  a sharp promontory or mountain peak. ∎  a raised projection on the pommel of a Western saddle: slung from the horn of his saddle was a leather bag. ∎  (the Horn) Cape Horn. ∎  an arm or branch of a river or bay. ∎  the extremity of the moon or other crescent. ∎ Brit., vulgar slang an erect penis. 4. a wind instrument, conical in shape or wound into a spiral, originally made from an animal horn (now typically brass) and played by lip vibration. ∎ short for French horn. 5. an instrument sounding a warning or other signal: a car horn.• v. [tr.] (of an animal) butt or gore with the horns.PHRASES: blow (or toot) one's own horn inf. talk boastfully about oneself or one's achievements.draw (or pull) in one's horns become less assertive or ambitious.on the horn inf. on the telephone: she got on the horn to complain.on the horns of a dilemma faced with a decision involving equally unfavorable alternatives.PHRASAL VERBS: horn in inf. intrude; interfere.DERIVATIVES: horn·ist / -ist/ n. (in sense 4).horn·less adj.horn·like / -ˌlīk/ adj.

horn.
1. Ionic, Composite, or Corinthian volute, but especially Ionic.

2. Strong-stemmed projections ending in stiff leaves commonly found on C13 Gothic capitals or crockets.

3. Projection at each corner of an altar, ash-chest, sarcophagus, or stele, also called acroterium or ear.

4. Each of four projecting portions of any abacus curved on plan.

5. Cornucopia or Horn of Plenty.

6. Projection of one member in framed work, as in the head of a door-frame, or the horn of a C19 sash-window.

horn in biblical and derived uses a horn is taken as an emblem of power and might, a means of defence or resistance.

In Christian iconography (except as in the horns of Moses), the representation of horns on the head of a person or supernatural being are a sign of evil. Horns were also fancifully said to be worn by a cuckold.

Recorded from Old English and of Germanic origin, the word comes from an Indo-European root shared by Latin cornu and Greek keras.
horn of plenty another name for a cornucopia.

See also gate of horn, horns, make a spoon or spoil a horn.

horn bony excrescence (often curved and pointed) on the head of cattle, etc.; instrument made from or in imitation of this OE.; pointed projection XIII; substance of it XV. OE. horn m., corr. to OS. horn m., OHG., ON. horn n. (Du. hoorn, G. horn), Goth. haurn n. :- Gmc. *χurnaz, -am, rel. to L. cornū, Skr. śŕṅga-, and further to Gr. Kéras; cf. HART.
Hence hornblende XVIII. — G. hornbook ABC tablet covered with horn. XVI.

horn Brass musical instrument traditionally used in hunting and ceremonies. They appeared in the opera orchestras of 17th-century Europe and in the 19th century with Wagner and Strauss. The modern instrument (French horn) consists of a coiled tube of conical bore that widens to a flared bell; most have three valves. It has a mellow tone.