pachydermatous vs thick-skinned

pachydermatous

adj
  • Thick-skinned; insensitive. 

  • Of or relating to the pachyderms. 

  • Like an elephant 

thick-skinned

adj
  • Having a thick skin. 

  • Insensitive to the feelings of others; callous. 

  • Not easily offended. 

How often have the words pachydermatous and thick-skinned occurred in a corpus of books? (source: Google Ngram Viewer )