from
The Collaborative International Dictionary of English v.0.48
Tabard \Tab"ard\, n. [OE. tabard, tabart; cf. Sp. & Pg. tabardo,
It. tabarro, W. tabar, LGr. tampa`rion, LL. tabardum.]
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. [Spelt
also {taberd}.]
[1913 Webster]
In a tabard he [the Plowman] rode upon a mare.
--Chaucer.
[1913 Webster]