oppression vs suppression

oppression

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

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

  • A feeling of being oppressed. 

suppression

noun
  • The act or instance of suppressing. 

  • A process in which a person consciously excludes anxiety-producing thoughts, feelings, or memories. 

  • The state of being suppressed. 

  • The entirety of acts aimed at stopping or preventing the enemy to execute such unwanted activities like firing, regrouping, observation or others. 

  • A subconscious adaptation by a person's brain to eliminate the symptoms of disorders of binocular vision such as strabismus, convergence insufficiency and aniseikonia. 

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