—adj.
1 a at right angles to the plane of the horizon. b (usu. foll. by to) Geom. at right angles (to a given line, plane, or surface).
2 upright, vertical.
3 (of a slope etc.) very steep.
4 (Perpendicular) Archit. of the third stage of English Gothic (15th-16th c.) with vertical tracery in large windows.
5 joc. in a standing position.
—n.
1 a perpendicular line.
2 a plumb-rule or a similar instrument.
3 (prec. by the) a perpendicular line or direction (is out of the perpendicular).
Derivatives:
perpendicularity n. perpendicularly adv.
Etymology: ME f. L perpendicularis f. perpendiculum plumb-line f. PER- + pendere hang
Useful english dictionary. 2012.