re·ta·ble 
(rētā′bəl, rĕtə-)
(rētā′bəl, rĕtə-)n.
A structure forming the back of an altar, especially:
a. An overhanging shelf for lights and ornaments.
b. A frame enclosing painted panels.
[French, from Spanish retablo, from alteration of Catalan retaule, from earlier reataula, from Medieval Latin retrōtabulum : Latin retrō-, retro- + Latin tabula, tablet, board.]
retablealtarpiece for the chapel of the Casa de Contratación at the Alcázar
Seville, Spain