1. A shoe for horses, consisting of a narrow plate of iron in form somewhat like the letter u, nailed to a horses hoof.
2. Anything shaped like a horsehoe crab.
3. (Science: zoology) The limulus of horsehoe crab.
(Science: medicine) Horsehoe head, a bat of the genus Rhinolophus, having a nasal fold of skin shaped like a horsehoe.