what are filly
What is a filly? This is just one of several words used to describe a horse's age and gender. The word is used to differentiate between a young male and female horse. All baby horses are called foal, but a filly, or filly foal means that the foal is female. Definition of Filly A female horse under four years of age is called a filly. A female horse over the age of four years is called a mare. The plural of filly is fillies.