flagship vs overlord

flagship

verb
  • To act as a flagship for. 

noun
  • The most important one out of a related group. 

  • The ship occupied by the fleet's commander (usually an admiral); it denotes this by flying his flag. 

  • The ship regarded as most important out of a group, e.g. a nation's navy or company's fleet. 

overlord

verb
  • To rule over; to domineer. 

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. 

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