The word became associated with an ambling horse, usually for hire. The place-name, through its famous association with horses and horse-drawn carriages, is also the root of the Spanish word jaca, a term used for a small breed of horse and the Sardinian achetta horse.

The term "Hackney carriage" has nothing to do with the London district of Hackney, but rather traces its roots back to the 17th century and the French word hacquenée, which referred to a small, sturdy horse suitable for hire or general riding. These horses were the "workhorses" of the era, known for their endurance. When horse-drawn vehicles began to be licensed for public hire in London in 1662, they became known as Hackney coaches, and later, Hackney carriages. In 2026, the term remains the official legal name for London's iconic "Black Cabs," distinguishing them from "Private Hire" vehicles (like Ubers or minicabs). This distinction is vital: only a licensed Hackney carriage has the right to be hailed on the street or wait at a designated taxi rank. The name is a literal nod to their history as "vehicles for hire" that have served Londoners for over 350 years. Even as the fleet has transitioned to modern, zero-emission electric vehicles like the LEVC TX, they are still registered and regulated under the ancient "Hackney Carriage" laws that require drivers to pass "The Knowledge"—the most difficult taxi driver test in the world.