cofferdam
NounWordNet 3.0
Noun (1)
- large watertight chamber used for construction under waterSynonyms: caissonpneumatic caisson
Webster's Dictionary (GCIDE)
Cofferdam \Cof"fer*dam\, n. A water-tight inclosure, as of piles packed with clay, from which the water is pumped to expose the bottom (of a river, etc.) and permit the laying of foundations, building of piers, etc. [1913 Webster]