Shim (noun)

A thin piece of material, such as metal, wood, or plastic, used to fill gaps or spaces between objects, or to adjust the level or alignment of an object.

Origin:

From middle english schymme, schime, from old english sċyme, sċīme ("thin slice, shaving").

Examples:

1. A metal shim was used to level the table.
2. The door was adjusted by inserting a wooden shim between the frame and the door.
3. A plastic shim was used to fill the gap between the window and the frame.
4. The shim was used to adjust the alignment of the engine.
5. A metal shim was used to level the machine.