from the GNU version of the Collaborative International Dictionary of English
- n. a caisson, closed at the top but open at the bottom, and resting upon the ground under water. The pressure of air forced into the caisson keeps the water out. Men and materials are admitted to the interior through an air lock. See Lock.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. large watertight chamber used for construction under water
Sorry, no etymologies found.