Columbarium

1. a. Rom. Antiq. A subterranean sepulchre, having in its walls niches or holes for cinerary urns; also one of these niches or recesses.
b. A similar structure in a modern crematorium.
2. A pigeon-house, dove-cote; a pigeon-hole.
3. A hole left in a wall for the insertion of the end of a beam.
Subtle thresholds