What does the word perpendicular mean?

Usage examples for perpendicular

  1. It was trying to the nerves, for while on one side rose a perpendicular wall of rock, on the other the precipice went sheer down for several hundred feet, with a roaring torrent at the bottom. – On the Banks of the Amazon by W.H.G. Kingston
  2. The lathe, however, need not be directly beneath the counter shaft as the belt will run on an angle as well as perpendicular. – A Course In Wood Turning by Archie S. Milton and Otto K. Wohlers
  3. Looking back at the solid and apparently perpendicular rock, nearly a mile high, it seemed impossible that any one could ascend to the top. – The Lure of the Camera by Charles S. Olcott