shim

The word 'shim' first appeared in English in the early 18th century, but its precise origin remains obscure. It is likely a specialized technical term from carpentry or metalworking that entered the general lexicon. One plausible theory suggests it may be a dialectal alteration of the word 'shimmy,' which itself is a variant of 'chemise,' referring to a thin, lining garment—a metaphorical link to a thin filler. Another possibility is that it is simply an invented word, perhaps onomatopoeic, suggesting the sound or action of fitting a thin piece into a space. Regardless of its murky beginnings, 'shim' has maintained a stable and precise meaning as a term for a thin spacer or wedge used in engineering and construction.

This word is a simplex form. It is a loanword of uncertain origin, likely from a dialectal or technical source, and functions as a single, unanalyzable morpheme in modern English.