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Meaning of sponson

spon•son

Pronunciation: (spon'sun), [key]
— n.
  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.
  3. a protuberance at the side of a flying-boat hull, designed to increase lateral stability in the water.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.