gaffer vs overseer

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. 

overseer

noun
  • The manager of a plantation of slaves. 

  • An officer responsible for the care of the poor, making out lists of voters and those who had not paid taxes, etc. 

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