shimnoun [ C ]
uk/ʃɪm//ʃɪm/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:
A small metal shim will be used to keep the pedals from sticking.
shimverb [ T ]
/ʃɪm//ʃɪm/to put a shim between two parts of something to make them fit together, or to prevent them rubbing against each other:
The baseboards have been cut, shimmed, sealed, and nailed.