callus vs teach

callus

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. 

verb
  • To form such hardened tissue. 

teach

verb
  • To pass on knowledge generally, especially as one's profession; to act as a teacher. 

  • To pass on knowledge to. 

  • To cause to know the disagreeable consequences of some action. 

  • To cause (someone) to learn or understand (something). 

noun
  • teacher 

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