obdurate vs pachydermatous

obdurate

adj
  • Hardened against feeling; hard-hearted. 

  • Stubbornly persistent, generally in wrongdoing; refusing to reform or repent. 

pachydermatous

adj
  • Thick-skinned; insensitive. 

  • Of or relating to the pachyderms. 

  • Like an elephant 

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