arcosolium
[ ahr-kuh-soh-lee-uh m ]
/ ˌɑr kəˈsoʊ li əm /
noun, plural ar·co·so·li·a [ahr-kuh-soh-lee-uh] /ˌɑr kəˈsoʊ li ə/.
(in Roman catacombs) an arched recess for a sarcophagus.