Shim/ʃɪm/ Definition 1 of 3Pro Tip 1/2Physical Adjustment Shims are for precision, they help make small adjustments to fit items together better. The mechanic used a shim for the engine parts to fit snugly. Pro Tip 2/2Construction Tool Shims are common in construction and home repair for stability and levelling. She inserted shims between the floorboards.