crown prince vs overlord

crown prince

noun
  • A person designated and raised to become the next king. 

  • A person expected to inherit or take over an enterprise or undertaking once its current manager retires or dies. 

  • A person designated and raised to become the next emperor. 

overlord

noun
  • A ruler of other rulers. 

  • A feudal lord directly owed rent or personal service by a tenant of subinfeudated land, a tenant's liege lord. 

  • Anyone with overarching power or authority in a given domain. 

verb
  • To rule over; to domineer. 

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