adjective

1. at right angles to a given plane or line
2. exactly upright; vertical; straight up or down
3. very steep
4. of or designating the third and latest style of English Gothic architecture of the 14th to the 16th cent., characterized by vertical lines in its tracery

Etymology: ME perpendiculer < OFr < L perpendicularis < perpendiculum, plumb line < perpendere, to weigh carefully < per-, intens. + pendere, to hang: see pendant

noun

1. a device used in finding or marking the vertical line from any point
2. a line at right angles to the plane of the horizon
3. a line or plane at right angles to another line or plane
4. a perpendicular or upright position