horn

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

• noun One of the hard, usually permanent structures projecting from the head of certain mammals, such as cattle, sheep, goats, or antelopes, consisting of a bony core covered with a sheath of keratinous material.
• noun A hard protuberance, such as an antler or projection on the head of a giraffe or rhinoceros, that is similar to or suggestive of a horn.
• noun The hard smooth keratinous material forming the outer covering of the horns of cattle or related animals.
• noun A natural or synthetic substance resembling this material.
• noun A container, such as a powder horn, made from a horn.
• noun Something having the shape of a horn, especially.
• noun A horn of plenty; a cornucopia.
• noun Either of the ends of a new moon.
• noun The point of an anvil.
• noun The pommel of a saddle.
• noun An ear trumpet.
• noun A device for projecting sound waves, as in a loudspeaker.
• noun A hollow, metallic electromagnetic transmission antenna with a circular or rectangular cross section.
• noun A wind instrument made of an animal horn.
• noun A brass instrument, such as a trombone or tuba.
• noun A French horn.
• noun A wind instrument, such as a trumpet or saxophone, used in a jazz band.
• noun A usually electrical signaling device that produces a loud resonant sound.
• noun Any of various noisemakers operated by blowing or by squeezing a hollow rubber ball.
• noun Slang A telephone.
• intransitive verb To join without being invited; intrude. Used with in.
• idiom (blow/toot) To brag or boast about oneself.
• idiom (draw/haul) /pull) To restrain oneself; draw back.
• idiom (draw/haul) /pull) To retreat from a previously taken position, view, or stance.
• idiom (draw/haul) /pull) To economize.
• idiom (on the horns of a dilemma) Faced with two equally undesirable alternatives.

from The Century Dictionary.

• To operate upon by means of a horn-press or horning-press. See horn, n., 4 .
• To furnish with horns.
• To cause to wear “horns” as the mark of a cuckold; cuckold.
• To give the shape of a horn to.
• To treat to a charivari, or mock serenade of tin horns, etc. See horning, 2.
• To adjust (the frames of a ship) in process of construction so that they shall be exactly at right angles with the line of the keel.
• noun In sheet-metal work, an attachment to a press which, in its most simple form, resembles the horn of an anvil. In seaming and pressing locked sheets of tin together it serves as the anvil on which the joined sheets are laid while the press bends the seams down. It gives name to the work of horning, or seaming with a horn, and to the horning-press, a press on which horning is done.
• noun In organ-building, a reed-stop with a tone like that of the French horn.
• noun In golf, same as bone, 10.
• noun The bare branch of a leafless tree. [Figurative.]
• noun One of the branches of the V-shaped comb found in such breeds of poultry as the Polish and La Flèeche.
• noun In archery: The tip at each end of a bow, usually made of horn and provided with a nock for fastening the bowstring.
• noun A reinforcement at the butt of an arrow, fitted with a nock to receive the bowstring: usually made of horn.
• noun The portion of a composite bow which is made of horn: see bow, 2.
• noun In machinery, a curved lever, pivoted on the side of a planing-machine, which, on being knocked over by the tappets on the moving table, gives, through a linkage, the reversing movement to the driving mechanism.
• noun An excrescent growth upon the head in certain animals, serving as a weapon of offense or defense. See def. 3.
• noun An antler of a deer.
• noun Hardened and thickened epidermis or cuticle, as that of which nails, claws, and hoofs consist, differing from hair or other cuticular structures chiefly in density and massiveness.
• noun Something made of horn, or like or likened to a horn in position, shape, use, or purpose.
• noun Specifically— A feeler; a tentacle; an antenna; an ovipositor; also, the tuft of feathers upon the head of sundry birds, resembling a horn; a plumicorn, as that of various owls.
• noun A wind-instrument more or less resembling a horn in shape and size, and originally made of horn: as, a hunting-horn; a tin horn. In the simpler forms the horn is used chiefly to give signals, producing single or slightly variable loud tones. The hunting-horn, however, was early elaborated and made capable of producing a variety of calls, fanfares, and simple tnnes. Wood, ivory, and various metals have been used for making horns.