noun

A flat, circular metal or rubber ring used to distribute the load of a threaded fastener (such as a bolt or screw) and prevent damage to the surface it is fastened to. A person or machine that washes something.

Example

1. Make sure you use a washer under each bolt to prevent the metal from being damaged.
2. The mechanic tightened the nut with a wrench and then added a washer for extra security.
3. The car washers worked quickly to clean all the vehicles in the lot.