Wheel definition
A circular device, thin in relation to its face area, usually able to rotate about a central axle or pivot, with a durable but elastic rim or with regular teeth cut on the rim and for lightness often supported by spokes joined to the hub instead of being left solid. The invention of the wheel enabled loads to be transported with relative ease, because rolling friction is always much less than sliding friction . The use of cogged wheels also enabled power to be transmitted from one component to another. Also see alloy wheel , chain wheel , chopped wheel , degree wheel , disc wheel , and drag wheel .