riser vs tread

riser

noun
  • The vertical part of a step on a staircase. 

  • a reservoir built into a metal casting mold to prevent the formation of cavities in the casting as the metal shrinks on cooling. 

  • A platform or stand used to lift or elevate something. 

  • A Manx cat with a showable short tail. 

  • A pipe connecting an individual exhaust port of an internal combustion engine to the muffler, particularly on aircraft. 

  • A strip of webbing joining a parachute's harness to the rigging lines. 

  • A vertical utility conduit, pipe or path between floors of a building for placement of cables (e.g. telephone, networking), or to convey fluids (e.g. gas, water). 

  • Someone or something which rises. 

  • The main body of a bow. 

tread

noun
  • The horizontal part of a step in a flight of stairs. 

  • A step taken with the foot. 

  • The grooves carved into the face of a tire, used to give the tire traction. 

  • The chalaza of a bird's egg; the treadle. 

  • The grooves on the bottom of a shoe or other footwear, used to give grip or traction. 

  • A bruise or abrasion produced on the foot or ankle of a horse that interferes, or strikes its feet together. 

  • The top of the banquette, on which soldiers stand to fire over the parapet. 

  • The act of avian copulation in which the male bird mounts the female by standing on her back. 

  • A manner of stepping. 

  • The sound made when someone or something is walking. 

verb
  • To proceed, to behave (in a certain manner). 

  • To beat or press with the feet. 

  • To work a lever, treadle, etc., with the foot or the feet. 

  • To crush grapes with one's feet to make wine 

  • To step or walk upon. 

  • To copulate; said of (especially male) birds. 

  • To step or walk (on or across something); to trample. 

  • To go through or accomplish by walking, dancing, etc. 

  • To copulate with. 

  • To crush under the foot; to trample in contempt or hatred; to subdue. 

How often have the words riser and tread occurred in a corpus of books? (source: Google Ngram Viewer )