A padded jacket or tunic, covering the trunk and thighs, and worn under, or occasionally over, mail or plate armour.
The gambeson was made from linen, or sometimes silk, padded with wool, cotton or other soft material, and quilted. It was also sometimes worn alone as an alternative to mail or plate armour.
Middle English. From Anglo-Norman gambesoun, gambesun, gambisoun, gaumbesoun, Anglo-Norman and Middle French gambeson, Old French, Middle French gambison from Old French, Middle French gambais, wambeis, in similar meaning + -on.