callus vs indulge

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. 

indulge

verb
  • To grant an extension to the deadline of a payment. 

  • To give way to (a habit or temptation); to not oppose or restrain. 

  • To satisfy the wishes or whims of. 

  • To grant as by favour; to bestow in concession, or in compliance with a wish or request. 

  • To yield to a temptation or desire. 

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