bitterness vs ressentiment

bitterness

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

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

  • The quality of having a bitter taste. 

  • Harsh cold. 

ressentiment

noun
  • A sense of resentment arising from suppressed feelings of envy and hatred, often leading to a frustrated sense of inferiority, with various social repercussions. 

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