What is another word for "horizontality"?

Roget's Thesaurus (1911) lists these synonyms for "horizontality": accubation, accumbent, all, alluvial, area, azimuth, back, beam, billiard, bowling, butte, calm, couch, couchant, cricket, croquet, dead, decumbence, decumbency, decumbent, discumbency, down, esplanade, estrade, even, fell, flat, flatness, flatten, floor, glass, green, ground, horizontal, horizontally, instrument, its, jacent, knock, land.