Definition of "gambeson"

Although the gambeson was chiefly worn under the coat of mail, to protect the body from being bruised by the strokes of the sword or lance, a circumstance that might happen without a division of the mail, the verses quoted in the Siege of Karleverok, shew that it was sometimes worn as a fur coat, and ornamented with rich decorations.

1786, Francis Grose, A Treatise on Ancient Armour and Weapons, page 18