[ noun ] a painted or carved screen placed above and behind an altar or communion table <noun.artifact>
Altarpiece \Al"tar*piece`\, n. The painting or piece of sculpture above and behind the altar; reredos.
A few years ago, an heretical scholar even suggested that the famous 'Adoration of the Magi' altarpiece in Cologne Cathedral is not by Lochner.
There is no comparison. But it is the mysterious 'Entombment', dated about 1500 to fix it to a known commission for an altarpiece for Sant'Agostino and painted in oil, which is the greater puzzle.