What is another word for "flatness"?

Roget's Thesaurus (1911) lists these synonyms for "flatness": accubation, accumbent, all, alluvial, and, area, azimuth, back, beam, billiard, blanket, board, book, boring, bowling, butte, calm, caught, cold, commonplace, conte, couch, couchant, cricket, croquet, damp, dead, deadly, dearth, decumbence, decumbency, decumbent, depress, discoid, discumbency, ditch, down, dry, dull, dullness.