What term is used to describe an uncastrated male horse?

The term used to describe an uncastrated male horse is "stallion." A stallion typically refers to a mature male horse that has not undergone castration, allowing it to retain its reproductive capabilities. This term is often used in breeding contexts, where stallions are valued for their genetic contribution and ability to sire offspring.

In contrast, a colt specifically refers to a young male horse, generally under the age of four, and while colts can eventually become stallions if they are not castrated, the term "stallion" is more comprehensive and indicates maturity. A gelding is a male horse that has been castrated, affecting its ability to breed. Meanwhile, a mare is a term reserved for female horses. Thus, "stallion" is the correct term for an uncastrated male horse, capturing both its gender and its reproductive status.