If something is shimmed, it means that a small piece of material is put in a space to make it the right size or shape.
Shimmed can make people think of fixing things or making things fit just right.
Examples:
He shimmed the table to make it stop wobbling.
The door was shimmed so it would close properly.
She shimmed the window to keep the cold air out.
The wobbly chair was shimmed with a piece of paper.
The tiny car was shimmed to fit in the small garage.
I shimmed the puzzle piece to make it fit perfectly.