An Etymological Dictionary of the German Language/Annotated/Wams
Wams, masculine, ‘doublet, jerkin, waistcoat,’ from Middle High German wambeîs, wambes, neuter, ‘doublet, garment worn under the coat of mail’; a Romance loan-word; compare Old French gambais. Middle Latin wambasium is itself a derivative of Old High German and Gothic wamba, ‘body.’