What is a Tabard? - Achaea Online Help

18.10.2 What is a Tabard?

A tabard is a loose-fitting garment something vaguely like an overcoat. If you
have seen almost any Knight, then you know what a tabard is - like the Three
Musketeers wore.

According to m-w.com - a short loose-fitting sleeveless or short-sleeved coat
or cape; a tunic worn by a knight over his armour and emblazoned with his arms;
a herald's official cape or coat emblazoned with his lord's arms.

According to www.dictionary.com - A short, heavy cape of coarse cloth formerly
worn outdoors; a tunic or capelike garment worn by a knight over his armour and
emblazoned with his coat of arms.

dictionary.cambridge.org does not provide a definition.

According to the Oxford English Dictionary: A garment of coarse material; a
loose upper garment without sleeves; formerly worn out of doors by the lower
classes, also by monks and foot-soldiers.