Horn (noun)

1. A hard bony outgrowth of the head of certain mammals, such as cattle, goats, and sheep, used especially for defense, in tossing opponents, and in music.
2. An instrument made of brass or other metal, with a flared bell and three valves, used especially in jazz and dance bands.
3. Something resembling a horn in shape or position, especially: a projecting part of an automobile, locomotive, or other vehicle.
4. A wind instrument consisting of a metal or wooden tube with a flared end, either straight or curved, sounded by the vibration of the player's lips against the mouthpiece.
5. A hornlike appendage, such as a growth on a tree or the angle of a corner.

Origin:

Middle english horne, from old english hyrne; akin to old high german hurna horn, latin cornu, greek keras.

Examples:

1. The cattle were equipped with sharp horns for self-defense.
2. She played the horn beautifully in the concert last night.
3. The train blew its horn as it approached the crossing.
4. The hunters used horns to signal to each other in the forest.
5. The car has two horns in the front and two in the back.