An archaic or obsolete term with no clearly established modern meaning; possibly related to chess or a crafted object.
Possibly a compound of chess + art, or an entirely separate Middle English term; the etymology cannot be reliably established.
Some old words are so obscure they vanished before anyone wrote down what they meant—'chessart' might have been perfectly ordinary to a 14th-century craftsperson but incomprehensible to us now.
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