callus vs ply

callus

noun
  • The new formation over the end of a cutting, before it puts out rootlets. 

  • A shining area on the frons of many species of Tabanomorpha (horse flies and relatives). 

  • The material of repair in fractures of bone; a substance exuded at the site of fracture, which is at first soft or cartilaginous in consistency, but is ultimately converted into true bone and unites the fragments into a single piece. 

  • A hardened area of the skin (especially on the foot or hand) caused by repeated friction, wear or use. 

verb
  • To form such hardened tissue. 

ply

noun
  • A strand that, twisted together with other strands, makes up rope or yarn. 

  • In two-player sequential games, a "half-turn" or a move made by one of the players. 

  • A layer of material. 

  • A bent; a direction. 

  • A condition, a state. 

verb
  • To work at (something) diligently. 

  • To press upon; to urge persistently. 

  • To persist in offering something to, especially for the purpose of inducement or persuasion. 

  • To travel over (a route) regularly. 

  • To bend, to flex; to be bent by something, to give way or yield (to a force, etc.). 

  • To wield or use (a tool, a weapon, etc.) steadily or vigorously. 

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