gaffer vs overman

gaffer

noun
  • The leader of a group or team, such as a boss, foreman, coach, publican. 

  • A chief lighting technician for a motion-picture or television production. 

  • The baby in the house. 

  • A sailor. 

  • An old man. 

  • A glassblower. 

overman

noun
  • A person who supervises others; a supervisor, especially in a mine. 

  • A person with great powers; a superman. 

verb
  • To provide with too many personnel; overstaff. 

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