Definition of "caisson" [cais•son]

• A watertight structure within which construction work is carried on under water. (noun)
• See camel. (noun)
• A large box open at the top and one side, designed to fit against the side of a ship and used to repair damaged hulls under water. (noun)
• A floating structure used to close off the entrance to a dock or canal lock. (noun)
• A horse-drawn vehicle, usually two-wheeled, used to carry artillery ammunition and coffins at military funerals. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The term caisson is sometimes applied to flat air-tight constructions used for raising vessels out of water for cleaning or repairs, by being sunk under them and then floated; but these floating caissons are more commonly known as pontoons, or, when air-chambers are added at the sides, as floating dry-docks."
• "Exposure to such pressures is apt to be followed by disagreeable and even dangerous physiological effects, which are commonly referred to as caisson disease or compressed air illness."
• "It's called a caisson, which is a huge, watertight wooden box half the size of a city block."