perpendicular

adjective

• 1at an angle of 90° to a given line, plane, or surface or to the ground:dormers and gables that extend perpendicular to the main roofline
• at an angle of 90° to the ground; vertical:the perpendicular cliff
• so steep as to be almost vertical:houses seem to cling by blind faith to the perpendicular hillside

• 2 (Perpendicular) denoting the latest stage of English Gothic church architecture, prevalent from the late 14th to mid 16th centuries and characterized by broad arches, elaborate fan vaulting, and large windows with vertical tracery: the handsome Perpendicular church of St Andrew the Perpendicular style

noun

• a straight line at an angle of 90° to a given line, plane, or surface: at each division draw a perpendicular representing the surface line
• [mass noun] (usually the perpendicular) perpendicular position or direction:the wall declines from the perpendicular a little inward