dictatorship vs tyranny

dictatorship

noun
  • A type of government where absolute sovereignty is allotted to an individual or a small clique. 

  • Any household, institution, or other organization that is run under such sovereignty or autocracy. 

  • A government which exercises autocratic rule. 

tyranny

noun
  • A government in which a single ruler (a tyrant) has absolute power; this system of government. 

  • The office or jurisdiction of an absolute ruler. 

  • Extreme severity or rigour. 

  • Absolute power, or its use. 

  • A system of government in which power is exercised on behalf of the ruler or ruling class, without regard to the wishes of the governed. 

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