callus vs scarification

callus

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

  • 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. 

verb
  • To form such hardened tissue. 

scarification

noun
  • The scratching, etching, burning / branding, or superficially cutting designs, pictures, or words into the skin as a permanent body modification. 

  • A medieval form of penance in which the skin was damaged with a knife or hot iron. 

  • The act of scarifying: raking the ground harshly to remove weeds, etc. 

  • A route of administration for some vaccinations and tests: rather than hypodermic injection, the site is inoculated intradermally not with any injection but rather only with small, shallow pricks or scratches; the needle is not hollow. 

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