A "secret vault" refers to a hidden or secure place where valuable or sensitive items are stored for safekeeping or confidentiality purposes. Full definition
Early on in the narrative, you'll be tasked with visiting Cayde's (the Hunter Vanguard voiced by Nathan Fillion) secret vault on Earth. (selectbutton.com)
No secret vault of gold exists to bail Catholics out of this attorney - driven legal siege. (firstthings.com)
While you may not ever need a secret vault in your basement to hide recipes, we know that you have pride in your dishes. (americanspice.com)