columbarium n.

"subterranean sepulchre in ancient Roman places with niches for urns holding remains," 1540s, neuter of Latin columbarius, "dove-cote" (the funereal place so called from resemblance), literally "pertaining to doves;" from columba "dove, pigeon," a word of uncertain origin. Literal sense of "dove-cote" in English is attested from 1881.