CAISSON

cais·son

ˈkāˌsän,ˈkās(ə)n/

noun

1. a large watertight chamber, open at the bottom from which the water is kept out by air pressure and in which construction work may be carried out under water.  Used for building bridges like the one shown above.

2. [historical]a chest or wagon for holding or conveying ammunition.

3. [LOSA] a place where lawyers go to avoid all phone calls, people, and other distractions, while they delve into history and make it come to life.