Arming doublet

A gambeson (also aketon, padded jack or arming doublet) is a padded defensive jacket, worn as armour separately, or combined with mail or plate armour. It also doubled as a winter coat for wearers. Gambesons were produced with a sewing technique called quilting. Usually constructed of linen or wool, the stuffing varied, and could be for example scrap cloth or horse hair. During the 14th century, illustrations usually show buttons or laces up the front.

An arming doublet (also called aketon) worn under armour, particularly plate armour of fifteenth- and sixteenth-century Europe, contains arming points for attaching plates. Fifteenth century examples may include goussets sewn into the elbows and armpits to protect the wearer in locations not covered by plate. German gothic armour arming doublets were generally shorter than Italian white armour doublets, which could extend to the upper thigh. In late fifteenth century Italy this also became a civilian fashion. Men who were not knights wore arming doublets, probably because the garment suggested status and chivalry.

The term gambeson is a loan from Old French gambeson, gambaison, originally wambais, formed after the Middle High German term wambeis "doublet", in turn from Old High German wamba "stomach" (cognate to womb).

The term aketon, originally medieval French alcottonem, might be a loan from Arabic al-qutn "cotton (definite article - the cotton)."

...
Wikipedia