bitterness vs virulence

bitterness

noun
  • The quality of eliciting a bitter, humiliating or harsh feeling. 

  • The quality of having a bitter taste. 

  • Harsh cold. 

  • The quality of feeling bitter; acrimony, resentment; the quality of exhibiting such feelings. 

virulence

noun
  • The state of being virulent. 

  • A measure of how virulent a thing is. 

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