Perpendicular

Part of speech: noun (n.)

1. A line at right angles to the plane of the horizon; a vertical line or direction.

2. A line or plane falling at right angles on another line or surface, or making equal angles with it on each side.

Part of speech: adjective (a.)

1. Exactly upright or vertical; pointing to the zenith; at right angles to the plane of the horizon; extending in a right line from any point toward the center of the earth.

2. At right angles to a given line or surface; as, the line ad is perpendicular to the line bc. Perpendicular style (Arch.), a name given to the latest variety of English Gothic architecture, which prevailed from the close of the 14th century to the early part of the 16th; -- probably so called from the vertical style of its window mullions.