noun
also kel·son ˈkelsən, ˈkē(ə)l- also -lts-
( -s )
Etymology: probably of Scandinavian origin; akin to Danish & Norwegian kjølsvin, Swedish kölsvin, Norwegian dialect kjølsvill, probably from kjøl, köl keel (from Old Norse kölr ) + svin pig, from Old Norse svīnn — more at keel , swine
: a longitudinal structure in the framing of a ship to contribute stiffness, prevent local deformations, and distribute over a considerable length the effect of concentrated loads:
a. : a structure of timbers in a wooden ship parallel with and above the keel and fastened to it by long bolts passing through the floor timbers
b. : a deep continuous structure of plates and bars in a metal ship usually in the form of a strong I beam secured at its ends to the stem and the sternpost and connected at its upper and lower edges to the reverse frames and keel plates respectively — called also middle-line keelson, vertical keel ; see bilge keelson , side keelson ; ship illustration