"bundle of documents referring to some matter," 1880 (by 1868 as a French word in English), from French dossier "bundle of papers," from dos "back" (12c.), from Vulgar Latin *dossum, variant of Latin dorsum "back" (see dorsal). Supposedly so called because the bundle bore a label on the back, or possibly from resemblance of the bulge in a mass of bundled papers to the curve of a back. Old French dossiere meant "back-strap, ridge strap (of a horse's harness)."
updated on March 12, 2019