Synonyms of vertical

1 Syllable
sheer, straight, plumb, steep
2 Syllables
straightup, upward, erect, unbent, standup, upright, straightest, cocked, stand-up, straight-up, straighter
3 Syllables
uncurled, collinear, up-and-down
4 Syllables
rectilineal, erectile
5 Syllables
perpendicular