curb vs tread

curb

noun
  • A swelling on the back part of the hind leg of a horse, just behind the lowest part of the hock joint, generally causing lameness. 

  • Something that checks or restrains; a restraint. 

  • A concrete margin along the edge of a road; a kerb (UK, Australia, New Zealand) 

  • A riding or driving bit for a horse that has rein action which amplifies the pressure in the mouth by leverage advantage placing pressure on the poll via the crown piece of the bridle and chin groove via a curb chain. 

  • A sidewalk, covered or partially enclosed, bordering the airport terminal road system with adjacent paved areas to permit vehicles to off-load or load passengers. 

  • A raised margin along the edge of something, such as a well or the eye of a dome, as a strengthening. 

verb
  • To rein in. 

  • To bend or curve. 

  • To furnish with a curb, as a well; to restrain by a curb, as a bank of earth. 

  • To crouch; to cringe. 

  • To damage vehicle wheels or tires by running into or over a pavement curb. 

  • To check, restrain or control. 

  • To bring to a stop beside a curb. 

tread

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

  • 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. 

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

  • 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 curb and tread occurred in a corpus of books? (source: Google Ngram Viewer )