/spon"seuhn/ , 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. Aeron. a protuberance at the side of a flying-boat hull, designed to increase lateral stability in the water.
[ 1825-35; var. of EXPANSION ]