1. Caisson or lacuna, i.e. deep panel sunk in a ceiling, dome, soffit, or vault, often decorated in the centre with a stylized flower or similar embellishment, as on the undersides of Composite and Corinthian cornices. A ceiling, etc., with coffers is said to be coffered, and coffering is an arrangement of coffers.
2. Cavity in a thick wall, pier, etc., filled with rubble and other material, often box-like compartments formed by the facing-stones and cross- or bonding-stones.
cof·fer / ˈkôfər; ˈkäfər/ • n. 1. a strongbox or small chest for holding valuables. ∎ (coffers) the funds or financial reserves of a group or institution: the federal government's empty coffers.2. a recessed panel in a ceiling.DERIVATIVES: cof·fered adj. (in sense 2).