acclimatize vs make callous

acclimatize

verb
  • To make used to a new climate or one that is different from that which is natural; to inure or habituate to other circumstances; to adapt to the peculiarities of a foreign or strange climate. 

  • To get used to a new climate. 

make callous

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