A device such as a plumb line that is used in making or marking a perpendicular line.
A line or plane that is perpendicular to another.
at or forming a right angle (to something).
Exactly upright; extending in a straight line toward the centre of the earth, etc.
Independent of or irrelevant to each other; orthogonal.
Synonym of slash ⟨/⟩ in its use to mark the amount of shillings in a sum or (obsolete) in all its uses.