rancor vs ruthlessness

rancor

noun
  • Rancidity, rankness. 

  • A feeling of long-lasting ire for another, sometimes to the point of hatred, over a perceived wrongdoing; bitterness. 

ruthlessness

noun
  • The property of being ruthless. 

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