The word "colt" is often used to refer to any baby horse—but this is incorrect. The proper gender-neutral term for a young horse is "foal." All colts are foals, but foals can be either fillies or colts, in the same way that all infant boys are babies, but babies can be either infant boys or infant girls.
The Definition of "Colt"
Strictly speaking, a colt is an uncastrated (intact) male horse, pony, donkey, or mule younger than four years of age. The word is pronounced to rhyme with "bolt." The term's proper usage takes into account the fact that the baby horse is a male. For example, "The colt and filly played in the paddock while their mothers grazed nearby." The sentence would be equally correct if stated thus: "The two foals played in the paddock..." but the first example specifies the genders of the foals.
Common Usages of "Colt"
People frequently and incorrectly refer to all baby horses as colts, but as previously mentioned, this is incorrect. It’s a common mistake often encountered in movies and books.
A very young horse may be called a "filly foal" or "colt foal." When a colt is weaned, it may be called a "weanling colt," and when it reaches the age of one, it may be called a "yearling colt" (or simply "yearling"). You might hear a colt over the age of one or two called a "stud colt."
Characteristics of Colts
A popular notion is that fillies are smarter than colts. Likewise, some people believe that fillies stand more quickly after birth and nurse sooner after they are born than fillies do. These are merely popular myths. Many people believe that colts are bolder than fillies, but a 2010 study suggests that this, too, is untrue. Like most mammalian males, colts tend to grow a bit faster than fillies—even moreso if they are gelded at a young age. This is because gelding—the practice of removing the colt's testes, also known as castration or neutering—refocuses the colt's reproductive growth into other aspects of development.
Other Horse-Related Definitions
The horse-racing world has a stricter definition of the word "colt": a young male horse between the ages of two and five. Races for colts and fillies are commonplace. After the age of five, colts are called either stallions or geldings. In a race, a filly may be any female horse younger than five years old. After the age of four, a filly is called a mare.
All young equids, including donkeys, ponies, mules, zebras, and onagers, share the definitions of "colt" and "filly." Thus, you might hear someone talking about a donkey filly or pony colt.
Colts in Popular Culture
The word "colt" comes from the Old English expression for "young ass." In Biblical times, the term was also used for young camels. It's similar to the Swedish kult, which referred to a young boar or piglet, or to a boy. The Danish kuld meant "offspring" or "brood" and was used as early as the 13th century as a term for a child.
In Classical Dictionary of the Vulgar Tongue (published in 1796), an old man who married or kept the company of a young girl was said to have "a colt's tooth in his head."
A nursery rhyme from Old Mother Goose mentions colts, as well:
Shoe the colt,
Shoe the colt,
Shoe the wild mare;
Here a nail,
There a nail,
Colt must go bare.
The Indianapolis Colts are a team in the National Football League.