arca, archa

1. Space in a vaulted chamber for sepulchral purposes, e.g. arcosolium or loculus.

2. Excavation before the basement-walls of a building.

3. Mortuary-chest, shrine, pyx, or receptacle for relics.

4. Prison or secure chamber.

5. Caisson for building bridges.

6. Roof-beam with a groove running its length.