18c., "woman's underbodice," from French brassière "child's chemise; shoulder strap" (17c.), from Old French braciere "arm guard" (14c.), from bras "an arm," from Latin bracchium (see brace (n.)). Modern use is a euphemistic borrowing employed in the garment trade by 1902.[brassiere etymology, brassiere origin, 英语词源]