Gelding

A gelding is a castrated horse or other equine such as a donkey or a mule. Castration, and the elimination of hormonally driven behavior associated with a stallion, allows a male horse to be calmer and better-behaved, making the animal quieter, gentler and potentially more suitable as an everyday working animal. As a verb, "gelding" or "to geld" refers to the castration procedure itself.