vault (1)EnglishOxford American Thesaurusvault1 noun 1 the vault was supported on eight massive stone piers: arched roof, arched ceiling, dome, arch. 2 the vault under the church: cellar, basement, underground chamber, crypt, undercroft, catacomb, cavern; burial chamber, tomb, sepulcher. 3 valuables stored in the vault: strongroom, safe deposit, safety deposit, safe, repository, depository, treasury.