What is the male stallion called?

Answer 1

Stallions are always male. They do not have a special name. When male horses are younger then 6 months of age they are called colts. But once they reach 6 months they are called weanlings. Once they are a year old they are either called stallions or geldings. But stallion and gelding does not mean the same thing. The difference between a stallion and a gelding is that a gelding was gelded. Which means he can no longer mate, even though he might want to.
I am not sure what you think a stallion IS? A stallion IS a male horse, an intact one who hasn't been gelded (Castrated). A male horse who has been gelded is called a gelding.
A stallion is a male horse that has been "gelded", i.e. castrated, i.e. neutered, i.e subjected to a bilateral orchiectomy, i.e. emasculated - so by definition, a stallion IS male. Once you use the word stallion, adding the word male is redundant.

Answer 2

Stallion is the term used for a male horse that can breed/ reproduce. Gelding is a term for a male horse who has been castrated. Colt is the term for a male horse under four years old.