onus vs oppression

onus

noun
  • Responsibility; burden. 

  • A legal obligation. 

  • Burden of proof, onus probandi. 

  • Stigma. 

  • Blame. 

oppression

noun
  • The exercise of authority or power in a burdensome, cruel, or unjust manner. 

  • The act of oppressing, or the state of being oppressed. 

  • A feeling of being oppressed. 

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