definition of axle
An axle is a rod around which a wheel moves or rotates. The front wheels of your car sit on an axle, turning around it as the car moves. Any kind of vehicle with wheels uses some kind of axle for those wheels to rotate on. Trucks, buses, and cars have axles, and so do lawnmowers and wagons and even bicycles. The original, Middle English word for axle was axle-tree, which came from a combination of the Old Norse word Ã¶xull and the Old English eax, both of which mean axis, or line around which a body rotates.