Tabard

Webster's Dictionary

(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.

The Nuttall Encyclopedia

A tunic without sleeves worn by military nobles over their arms, generally emblazoned with heraldic devices. "Toom Tabard," empty king's cloak, nickname given by the Scotch to John Balliol as nothing more.