0 a small object or piece of material used between two parts of something to make them fit together, or to prevent them rubbing against each other:
1 to put a shim (= a small object or piece of material) between two parts of something to make them fit together, or to prevent them rubbing against each other:
Before a race, he uses razor-thin shims to align the runners to .005 of an inch accuracy.
The repair involves installing a steel shim a couple of millimetres thick in the pedal assembly.
To bore perfectly square, deep holes, shimming the table where it joins its column support casting is necessary.
Small, broken stones shim the base of a large monument bearing the family name.
In situations like these shims are most often used.
Shims are used to snug up contact between the crib and supported object or change the direction of the crib (tilt).