The Collaborative International Dictionary
Superaltar
Superaltar \Su"per*al`tar\, n. (Arch.) A raised shelf or stand on the back of an altar, on which different objects can be placed; a predella or gradino.
Wiktionary
superaltar
n. (context architecture English) A raised shelf or stand on the back of an altar, suitable for holding objects; a predella or gradino.