The word sire in the horse world is usually used in place of the father. A horse’s father is the sire, and so is the horse’s male parent. A foal’s sire then is the stallion who was bred to the mare to produce that foal. A mare can't be a sire, as sire only refers to the male antecedents of a horse.
The sire can be used in the past tense. If a certain stallion is a foal’s father, it is said to have sired that foal.
The word sire has its roots in French, Latin, and Old English and is related to the French word, monsieur, which means "my lord." So the roots of the word and its general use is quite old. It’s rare to hear it used outside of talk about livestock.
Grandsire and Granddam
Just as your grandfather is your father’s father or your mother’s father, a grandsire is the sire of a foal’s sire. While generally, grandsire could refer to the sire of either the mare or stallion that produces a foal, there is another distinction that can be made. But first, you must understand the meaning of the word dam.
A foal’s mother is called its dam. And, a foal’s grandmother on either side could be called its granddam. But, to specify the dam’s male parent, the word damsire is used. So, a foal’s grandfather on the mother’s side is its damsire. All of the horses on the female side of a foal’s parentage are said to be on the damside. Or, another unusual word, distaff, may be used to talk about the mare’s pedigree. So the dam side can also be called the distaff side. In the racehorse world, a distaff race is only run by female horses.
Both dam and distaff have their roots in early French and English. Dame is the French word for woman, and distaff came to be used to refer to women because of a tool used in spinning, which was regarded as women’s work.
On a horse’s pedigree, the dam or distaff side always appears on the bottom of the page. The sire’s pedigree is listed first.
Get and Progeny
You may also run across the word progeny. Collectively, all of a stallion's or sire’s offspring are called its progeny. The plural of progeny is progenies. If you are referring to a single offspring, the word get may be used. Get, however, may also be used to refer to the sire’s offspring collectively, too. The quality of a stallion’s get or progeny is the ultimate proof of his worth as a breeding animal. When researching a stallion to potentially breed a mare, good breeders will ideally look at the progeny or get, and assess their temperament, conformation, and performance records.