WordNet sense 1 (a high pommel of a Western saddle (usually metal covered with leather)):

saddle horn

WordNet sense 2 (a brass musical instrument consisting of a conical tube that is coiled into a spiral and played by means of valves):

French horn

WordNet sense 3 (a brass musical instrument with a brilliant tone; has a narrow tube and a flared bell and is played by means of valves):

cornet, trump, trumpet

WordNet sense 4 (a device on an automobile for making a warning noise):

hooter, automobile horn, car horn, motor horn

WordNet sense 5 (stab or pierce with a horn or tusk):

tusk