Tholos.
Actually, the word camera is Latin or Greek for a vault or a chamber.
Latin. "Cave" is from the Old French "cave" (a cave, vault, cellar; 12c.), from Latin "cavea" (hollow).
Tagalog word for vault: pagtalon
Vault only has one syllable. This means the whole word is the syllable.
open area
vault
Another word for crypt is mausoleum or vault.
There is 1 syllable.
Cellar, vault, crypt?
If you are assuming the first definition for the word vault is an arched structure, then I suppose the space under an arched structure would be number two.
grave, repository, vault, burial
That rogue is in the vault right now!