Old English horn "horn of an animal," also "wind instrument" (originally made from animal horns), from Proto-Germanic *hurnaz (cf. German Horn, Dutch horen, Gothic haurn), from PIE *ker- "horn; head, uppermost part of the body," with derivatives refering to horned animals, horn-shaped objects and projecting parts (cf. Greek karnon "horn," Latin cornu "horn," Sanskrit srngam "horn," Persian sar "head," Avestan sarah- "head," Greek koryphe "head," Latin cervus "deer," Welsh carw "deer"). Reference to car horns is first recorded 1901. Figurative senses of Latin cornu included "salient point, chief argument; wing, flank; power, courage, strength." Jazz slang sense of "trumpet" is by 1921. Meaning "telephone" is by 1945.
