cavo-rilievo

from The Century Dictionary.

• noun In sculpture, a kind of relief in which the highest surface is level with the plane of the original stone, which is left around the outlines of the design.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Sculp.) Hollow relief; sculpture in relief within a sinking made for the purpose, so no part of it projects beyond the plain surface around.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun art sculpture in relief within a sinking made for the purpose, so no part of it projects beyond the surrounding surface