ball-bearing

The term is a transparent compound from the late 19th century, directly describing the device's core components and function. The first element, 'ball', refers to the small, hard spheres that are the primary rolling elements. The second element, 'bearing', derives from the mechanical sense of a component that 'bears' or supports a load while allowing constrained motion. The compound's logic is perfectly literal: a 'bearing' that uses 'balls' to carry loads with minimal friction. This invention was pivotal in the Industrial Revolution, enabling high-speed, low-friction rotation in machinery from bicycles to complex manufacturing equipment, with the name elegantly capturing its essential mechanical principle.

Structure: ball (sphere) + bearing (supporting part) - ball: From Middle English bal, from Old English beall or Old Norse bǫllr, meaning a rounded object or sphere. In this compound, it denotes the spherical shape of the rolling elements. - bearing: From the verb bear (to carry, support) + the suffix -ing, forming a noun that denotes a part that supports a load and facilitates motion.