Tabard

n. short heavy cloak; loose outer garment worn by a knight; garment worn by a herald and decorated with his master's coat of arms

A tabard is a short coat, either sleeveless, or with short sleeves or shoulder pieces, which was a common item of men's clothing in the Middle Ages, usually for outdoors. It might be belted, or not. Tabards might be emblazoned on the front and back with a coat of arms, and in this form they survive now as the distinctive garment of officers of arms in heraldry.
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Noun
1. a short sleeveless outer tunic emblazoned with a coat of arms; worn by a knight over his armor or by a herald
(hypernym) tunic

n. tabard, short heavy cloak; loose outer garment worn by a knight; garment worn by a herald and decorated with his master's coat of arms

(n.)
A sort of tunic or mantle formerly worn for protection from the weather. When worn over the armor it was commonly emblazoned with the arms of the wearer, and from this the name was given to the garment adopted for heralds.