callus vs scarify

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. 

scarify

verb
  • To scratch, etch, burn, or cut designs into one's skin as a form of body modification. 

  • To harrow the feelings. 

  • To remove thatch (build-up of organic matter on the soil) from a lawn, to dethatch. 

  • To break up, loosen, or roughen the surface of a field or road or a hard surface. 

  • To damage the testa (seed coat) of a seed by cutting, scraping, chemicals, hot water, or fire to allow permeation of water and faster germination. 

  • To make scratches or cuts on. 

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