callus vs inure

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. 

inure

verb
  • To cause someone to become accustomed to something that requires prolonged or repeated tolerance of one or more unpleasantries. 

  • To take effect, to be operative. 

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