[kaw-fer-dam, kof-er-]
  1. a watertight enclosure placed or constructed in waterlogged soil or under water and pumped dry so that construction or repairs can proceed under normal conditions.
  2. Nautical. a sealed void between two bulkheads, as for insulation or as an extra barrier to the escape of liquids or vapors.

Origin of cofferdam

First recorded in 1730–40; coffer + dam1 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for cofferdam

Historical Examples of cofferdam

  • The lower part of C bulkhead was doubled and was in the form of a cofferdam.

  • The whole was built in a cofferdam, quite dry, and the opening was a holiday.

  • And the night shift began to repair the cofferdam for old Jezebel had dropped suddenly back into her old trail.

    Still Jim

    Honor Willsie Morrow

  • A hand pump served to keep the cofferdam dry enough for excavating; but in more open material a power pump is usually required.

    Concrete Construction

    Halbert P. Gillette

  • The foundations were put down by means of a cofferdam which was kept dry by pumping.

    Concrete Construction

    Halbert P. Gillette

British Dictionary definitions for cofferdam


  1. a watertight structure, usually of sheet piling, that encloses an area under water, pumped dry to enable construction work to be carried out. Below a certain depth a caisson is required
  2. (on a ship) a compartment separating two bulkheads or floors, as for insulation or to serve as a barrier against the escape of gas or oil
Often shortened to: coffer
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012