Per·pen·dic·u·lar 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. Geom. 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.


 perpendicular style
      n : a Gothic style in 14th and 15th century England;
          characterized by vertical lines and a four-centered
          (Tudor) arch and fan vaulting [syn: perpendicular, English-Gothic,
           English-Gothic architecture]