What is a castrated male horse called?

A castrated male horse is known as a gelding. Castration is the process of removing the testicles of a male horse, which alters its hormonal balance and typically results in a more docile and manageable animal. This procedure is often performed to make the horse easier to handle, especially in training and competition settings, and can help reduce aggressive behaviors associated with the stallion's hormones.

In contrast, a stallion refers to an uncastrated male horse, while a mare is an adult female horse. The term colt is used to describe a young male horse that has not yet reached maturity, and it does not imply the animal has been castrated. Thus, the correct term for a castrated male horse is indeed a gelding.