sub-lieutenant vs underling

sub-lieutenant

noun
  • A commissioned officer of the navy ranking above an acting sub-lieutenant and below a lieutenant. 

  • A commissioned officer of the Royal Navy ranking above a midshipman and below a lieutenant. 

underling

noun
  • A subordinate, or person of lesser rank or authority. 

  • A low, wretched person. 

How often have the words sub-lieutenant and underling occurred in a corpus of books? (source: Google Ngram Viewer )