a piece of clothing that covers your chest and back and has no sleeves, worn over a shirt or jacket 〔遮住胸背部，穿在衬衫或夹克外面的〕无袖外套
Examples from the Corpus
tabard• Once, the King sent a herald with banner, trumpet and tabard, to invite the captain of Famagusta to surrender.• The royal tabard was soaked in blood.• Gabriel put on his white shirt and scarlet tabard with the gold embroidery.