What is another word for "keel"?

Roget's Thesaurus (1911) lists these synonyms for "keel": about, anastrophe, and, base, baseboard, based, basement, basis, before, bilge, bottom, built, capsize, cart, centerboard, contraposition, contrariety, contrary, dado, deck, down, earth, eversion, flag, floor, foot, footing, foundation, fundamental, ground, hardpan, head, heavy, hold, hoof, horse, hypallage, hyperbaton, inside, introversion.