fillys

A filly is a young female horse, typically under the age of four. The term specifically refers to the gender and age of the animal. The word "filly" originates from Old English and is related to the word "foal." Male young horses are called colts. Filly is used in contrast to a mare, which is a mature female horse. The transition from filly to mare usually occurs when the horse reaches four years of age, though this can vary depending on breed and individual development.

Filly foals are born with the same physical and physiological characteristics as their male counterparts, but their development will diverge as they mature. They are often distinguished by their breed, temperament, and potential for riding or breeding. In equestrian sports, a filly's racing career or performance potential is often a subject of interest. Their training and handling are similar to colts, focusing on building trust, basic obedience, and eventually, specialized equestrian disciplines. The physical characteristics of a filly, such as bone structure and muscle development, continue to change rapidly during their first few years of life.