hackney

The word hackney has several related meanings, though many of them now sound old-fashioned. In its oldest and most direct sense, a hackney was a horse available for ordinary riding or for hire. Later, the word was also used for a carriage, and then for a cab that could be hired. In historical texts, if someone "takes a hackney," they are taking some kind of rented ride rather than using a private horse or carriage.

Because these animals and vehicles were in constant public use, the word developed a broader sense. It could refer to something ordinary, overused, or worn down by repeated service. It could even be used for a person whose work had become routine and dull, especially in older writing. The verb form also meant to make something common or stale through too much use.

That history explains the much more common modern adjective hackneyed. When an idea, phrase, or story is called hackneyed, it has been used so often that it no longer feels fresh. In other words, hackney is the older root, tied to hired horses and repeated use, while hackneyed is the form that most often survives in modern English.

So the heart of the word is use that has become too common. In older contexts it may point to a horse, carriage, or cab for hire; in extended use it suggests something made dull by constant repetition. If you know that connection, the modern meaning of hackneyed becomes much easier to remember.