[ spon-suhn ]

  1. a structure projecting from the side or main deck of a vessel to support a gun or the outer edge of a paddle box.

  2. a buoyant appendage at the gunwale of a canoe to resist capsizing.

  1. Aeronautics. a protuberance at the side of a flying-boat hull, designed to increase lateral stability in the water.

Origin of sponson

First recorded in 1825–35; variant of expansion

Words Nearby sponson

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use sponson in a sentence

  • The cutter jingled her full-speed bell while the tackle was still lifting the sponson boat.

  • He leaned on the rail and watched the departure of the officer of the faded blue cap with his crew of the sponson boat.

  • An eager gunner endeavoured to pass one of the tanks, but his gun caught the sponson and slipped off into the mud.

    A Company of Tanks | W. H. L. Watson
  • His tun of a torso bulged roundly out in front of me like the sponson of a battleship.

    Yellowstone Nights | Herbert Quick
  • A bomb exploded directly beneath the sponson, where the dead body had fallen.

    Life in a Tank | Richard Haigh

British Dictionary definitions for sponson


/ (ˈspɒnsən) /

  1. navy an outboard support for a gun enabling it to fire fore and aft

  2. a semicircular gun turret on the side of a tank

  1. a float or flotation chamber along the gunwale of a boat or ship

  2. a structural projection from the side of a paddle steamer for supporting a paddle wheel

  3. a structural unit attached to a helicopter fuselage by fixed struts, housing the main landing gear and inflatable flotation bags

Origin of sponson

C19: perhaps from expansion

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