1. A watertight structure within which construction work is carried on under water.
2. See camel (sense 2).
3. 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.
4. A floating structure used to close off the entrance to a dock or canal lock.
5. 1. A horse-drawn vehicle, usually two-wheeled, used to carry artillery ammunition and coffins at military funerals.
   2. A large box used to hold ammunition.

[French, from Old French, large box, alteration (influenced by caisse, chest) of casson, from Italian cassone, augmentative of cassa, box, from Latin capsa.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.