- a watertight enclosure placed or constructed in waterlogged soil or under water and pumped dry so that construction or repairs can proceed under normal conditions.
- a sealed void between two bulkheads, as for insulation or as an extra barrier to the escape of liquids or vapors.
- a watertight structure, usually of sheet piling, that encloses an area under water, pumped dry to enable construction work to be carried out. Below a certain depth a caisson is required
- (on a ship) a compartment separating two bulkheads or floors, as for insulation or to serve as a barrier against the escape of gas or oil
