Horseman

Definition:

(n.) A rider on horseback; one skilled in the management of horses; a mounted man.
(n.) A mounted soldier; a cavalryman.
(n.) A land crab of the genus Ocypoda, living on the coast of Brazil and the West Indies, noted for running very swiftly.
(n.) A West Indian fish of the genus Eques, as the light-horseman (E. lanceolatus).

Compare horseman with other words:

horseman vs. horsemen