A break down of terms to describe the age and sex of horses.
All horses, regardless of their date of birth, change their age on January 1st. Terms that are used to describe the sex and age of a horse include:
Foal - The offspring of horses, either male or female, up to one year of age.
Colt - Male offspring, up to four years of age.
Filly - Female offspring, up to four years of age or until the first breeding.
Mare - Mature female horse over four years of age or younger if bred.
Yeld Mare - Mature unfoaled female horse - has never given birth or is barren.
Stallion - Male horse that has not been gelded (casterated).
Gelding - Male horse that has been casterated of any age.
Yearling - A horse that is one year old up to two years old.
Weanling - A foal that has recently been weaned and no longer has access to its mother's milk.
Aged Horse - Any horse of any sex, over 10 years of age.