Jockey Victor Espinoza poses with American Pharaoh after winning the $1 million Arkansas Derby. (Danny Johnston/AP)

Every thoroughbred racehorse, no matter its actual birth date, becomes a 2-year-old on the second Jan. 1 of its life, and as 2-year-olds, racehorses need names. Before that age, trainers and grooms usually give the horses nicknames, or refer to them by their mother’s name and the year they born.

American Pharaoh, for example, was once “Littleprincessemma 2012.” To choose his permanent name, the Zayat family convened in January 2014 around good food, and called out their best suggestions for the nearly 50 new horses joining their stable.

The rules for naming a racehorse are as byzantine as the horse’s job is simple. You may not:

  • Name a horse using initials or numbers
  • End a name with “filly,” “colt,” “stud,” “mare,” “stallion,” or any other horse-related term
  • Name a horse after a living person without written permission
  • Use the name of a deceased person, unless approved by the Jockey Club, one of American horse racing’s governing bodies
  • Use the name of a track or stakes race
  • Use names with clear commercial or artistic value
  • Use names that are “obscene,” “vulgar” or “in poor taste.”
  • Use names identical or nearly identical to horses within certain time frames, depending upon what the original horse accomplished

After that, you get 18 characters. Spaces and punctuation count.

(Think you’ve come up with a name? Check the Jockey Club’s database to see if it’s already taken.)

“We try to give the horses names that are marketable and fun to say,” says Justin Zayat, president and CEO of Racing and Bloodstock, whose family owns Zayat Racing Stables, one of the more successful operations in the country. “We say the name and think, ‘Is this the one you’d want to hear your horse go down the finish line to. This name?’ “

Think about: Justin’s Quest, Key to the Nile, Presidential Oath and Solomini.

Those are all 3-year-olds in Zayat’s stable.

Justin’s Quest was named after Zayat. Key to the Nile, American Pharaoh’s half-brother, is named for his sire, Pioneerof the Nile. (Zayat misspelled “Pharaoh,” flipping the middle vowels, when registering the horse’s name. After he won the Triple Crown, the Jockey Club granted the horse both spellings, “Pharoah,” the original entry, and “Pharaoh.”)

Presidential Oath is named for his broodmare, Inaugurate. Solomini, running in the Kentucky Derby on Saturday, is named for Zayat’s nephew, who is named after both of his grandfathers, Solomon and David.

“Mostly, it’s after people we love,” Zayat said. “We name horses after a lot of people.”

That’s popular throughout the rest of the industry, too, said Linzay Marks of WinStar Farm in Versailles, Ky., the heart of horse country.

WinStar tries to stick to one-word names, like Justify or Audible, or short two-word names, like Noble Indy. All three thoroughbreds are running in the Derby. WinStar names horses after members of their bloodline, members of the farm’s (human) family or something catchy and maybe subtle.

Quip, for example, a 3-year-old colt, is named for his sire, Distorted Humor.

Read more on the Kentucky Derby:

2018 Kentucky Derby horses, odds and start time: Everything you need to know

Justify is set as the Kentucky Derby favorite in a deep field

The Kentucky Derby means mint juleps. Here are four variations.

Gronkowski the horse won’t run in Kentucky Derby but is eyeing Belmont Stakes

Rob Gronkowski, the human, buys a stake in Gronkowski, the racehorse