ˈ ̷ ̷ ̷ ̷ˌ ̷ ̷ noun
Etymology: coffer (I) + dam
1.
a. : a temporary watertight enclosure (as of piles packed with clay or of metal plates) from which the water is pumped to expose the bottom of a body of water and permit construction (as of foundations or piers)
b. : a watertight structure for making repairs below the waterline of a ship
2.
a. : a compartment formerly provided near the waterline of a man-of-war and filled with cellulose which would swell on contact with water and plug a hole
b. : the space between two closely located bulkheads in a ship