callus vs scar

callus

verb
  • To form such hardened tissue. 

noun
  • 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. 

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

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

scar

verb
  • To form a scar. 

  • To mark the skin permanently. 

  • To affect deeply in a traumatic manner. 

noun
  • A rock in the sea breaking out from the surface of the water. 

  • A permanent mark on the skin, sometimes caused by the healing of a wound. 

  • A cliff or rock outcrop. 

  • A bare rocky place on the side of a hill or mountain. 

  • A permanent negative effect on someone's mind, caused by a traumatic experience. 

  • Any permanent mark resulting from damage. 

  • A marine food fish, the scarus or parrotfish (family Scaridae). 

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