A large altarpiece in a cathedral.
altarpiece definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
an ornamental carving, painting, etc. above and behind an altar
altarpiece definition by American Heritage Dictionary
A piece of artwork, such as a painting or carving, that is placed above and behind an altar.