In standard English lexicography, a shim functions as both a noun and a verb referring to a thin, flat, or wedge-shaped piece of material—such as wood, metal, or plastic—inserted into a gap or crevice to level, adjust, align, or tightly space two objects apart. Historically, the word originated in late 19th-century regional terminology and has since become a standard technical term across carpentry, mechanics, and software engineering.