line manager vs overman

line manager

noun
  • The manager who is directly responsible for an employee. 

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 line manager and overman occurred in a corpus of books? (source: Google Ngram Viewer )