Yearling (horse)

A yearling is a young horse either male or female that is between one and two years old. Yearlings are comparable in development to a very early adolescent and are not fully mature physically. While they may be in the earliest stages of sexual maturity, they are considered too young to be breeding stock.

Yearlings may be further defined by sex, using the term "colt" to describe any male horse under age four, and "filly" for any female under four.