hackneys

Hackneys is the plural of hackney, a horse of medium size bred for ordinary riding or driving—workhorses rather than racehorses or warhorses.

The term extends to hackney carriages, horse-drawn vehicles for hire that became the original taxis.

From this comes the verb hackney, meaning to make common or trite through overuse, giving us hackneyed: hackneyed phrases, hackneyed ideas.

The connection is wear—what gets hired out constantly becomes worn down.