What is another word for "nadir"?

Roget's Thesaurus (1911) lists these synonyms for "nadir": base, baseboard, based, basement, basis, bilge, bottom, built, centerboard, dado, deck, earth, flag, floor, foot, footing, foundation, fundamental, ground, hardpan, hold, hoof, keel, mopboard, nethermost, pavement, paving, plinth, root, sole, substratum, substructure, support, toe, undermost, wainscot, work.