keelson
noun
keel·son ˈkel-sən 
ˈkēl-
ˈkēl- : a longitudinal structure running above and fastened to the keel of a ship in order to stiffen and strengthen its framework
Word History
Etymology
Middle English kelswayn, probably of Scandinavian origin; akin to Swedish kölsvin keelson
First Known Use
13th century, in the meaning defined above