Synonyms of horizontal

1 Syllable
smooth, straight, flush, flat
2 Syllables
level, even, planar, straightup, smoothed, unbent, standup, smoother, straightest, smoothest, reptant, evens, stand-up, straight-up, flushing, plane, prone, flusher, flattest, planed, straighter, smoothing
3 Syllables
decumbent, evener, regular, tabular, recumbent, aligned, uniform, uncurled, levelling, parallel, evened, invariant, procumbent, supine, collinear, accumbent, leveled, frictionless, planate
4 Syllables
complanate, vermicular, vinelike, rectilineal, mirrorlike, unfluctuating, resupine
5 Syllables
stoloniferous, perpendicular