vault1

noun

• 1a roof in the form of an arch or a series of arches, typical of churches and other large, formal buildings.
• literary a thing resembling an arched roof, especially the sky:the vault of heaven
• Anatomy the arched roof of a cavity, especially that of the skull:the cranial vault

• 2a large room or chamber used for storage, especially an underground one.
• a secure room in a bank in which valuables are stored.
• a chamber beneath a church or in a graveyard used for burials.

verb

• provide (a building or room) with an arched roof or roofs:a vaulted arcade
• make (a roof) in the form of a vault:there was a high ceiling, vaulted with cut slate