Noun

1. A wedge.
2. A kind of shallow plow used in tillage to break the ground, and clear it of weeds.
3. A thin piece of material, sometimes tapered, used for alignment or support.
4. A small library that transparently intercepts and modifies calls to an API, usually for compatibility purposes.

Verb

1. To fit one or more shims to a piece of machinery
2. To adjust something by using shims