Definition of: caisson

(kā′sən, -son) noun
1. An amfjmunition chest or wagon.
2. A two-wheeled vehicle carrying such a chest to serve a gun in firing position with its immediate needs in ammunition.
3. A large watertight chamber within which work is done under water, as on a bridge pier.
4. A watertight box, or other apparatus, to be placed beneath a sunken vessel and inflated in order to raise it.
5. A gate for closing the entrance to a drydock. [<F, aug. of caisse box, chest]
CAISSON
A. Airlocks.
B. Shafts for entrance of men and materials.
C. Work chamber.
D. Water level.
E. River bottom.
F. Bedrock.