Colt (horse)
From Simple English Wikipedia, the free encyclopedia
A Colt is a young male horse, under the age of four. Older male horses are called either a "stallion", if left fertile, or a "gelding" if neutered. The verb 'to geld' refers to the process of neutering a stallion.
A young female horse is called a filly until age four, and a mare thereafter.
A group of colts is called a "rag".