What is a castrated male horse called?

A castrated male horse is called a gelding.

Castration removes the testicles and usually reduces behaviors driven by reproductive hormones, such as some forms of aggression, mounting, and roaming. For this reason, geldings are often chosen for riding, work, and general handling, although temperament still depends on training, genetics, health, and management.

A stallion is an intact adult male horse. A colt is generally a young male horse, while a filly is a young female horse. These terms describe different things, so a young male cannot be called a gelding unless he has been castrated.

Gelding has been practiced for centuries in horse-keeping cultures. The timing of the procedure varies, and veterinary care is important because castration has potential complications. A gelding can still be athletic and successful in racing, sport, farm work, or recreational riding.