A hard growth of keratin that protrudes from the top of the head of certain animals, usually paired.
2
Any similar real or imaginary growth or projection such as the elongated tusk of a narwhal, the eyestalk of a snail, the pointed growth on the nose of a rhinoceros, or the hornlike projection on the head of a demon or similar.
3
An antler.
4
The hard substance from which animals' horns are made, sometimes used by man as a material for making various objects.