monarchy vs principate

monarchy

noun
  • The territory ruled over by a monarch; a kingdom. 

  • A government in which sovereignty is embodied within a single, today usually hereditary head of state (whether as a figurehead or as a powerful ruler). 

  • States based on a system of governance headed by a king or a queen. 

  • A form of government where sovereignty is embodied by a single ruler in a state and his high aristocracy representing their separate divided lands within the state and their low aristocracy representing their separate divided fiefs. 

principate

noun
  • A state ruled by a prince; a principality. 

  • The office of one who is principal or preeminent (such as a prince); the quality or status of being principal; preeminence. 

  • The early period of the Roman Empire, during which some characteristics of the government of the Roman Republic were retained; the reign of any particular emperor during said period. 

adj
  • Primary; principal. 

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