perpendicular

adjective
1. Mathematics. Intersecting at or forming right angles.
2. Being at right angles to the horizontal; vertical. See synonyms at vertical.
3. Often Perpendicular . Of or relating to a style of English Gothic architecture of the 14th and 15th centuries, characterized by emphasis of the vertical element.

noun
1. Mathematics. A line or plane perpendicular to a given line or plane.
2. A perpendicular position.
3. A device, such as a plumb line, used in marking the vertical from a given point.
4. A vertical or nearly vertical line or plane.