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Related to perpendicular: perpendicular slope
1. at right angles to a horizontal plane
2. denoting, relating to, or having the style of Gothic architecture used in England during the 14th and 15th centuries, characterized by tracery having vertical lines, a four-centred arch, and fan vaulting
3. Geometry a line or plane perpendicular to another
4. any instrument used for indicating the vertical line through a given point
5. Mountaineering a nearly vertical face
Line or plane that meets another at right angles.
Geometric objects are perpendicular if they intersect in an angle of 90°.