mayor of the palace vs mer

mayor of the palace

noun
  • In the Merovingian kingdoms, the king’s steward and, by the 7th century, de facto regent. 

mer

noun
  • merpeople 

  • A repeat unit: a structural unit which through repetition forms a polymer. 

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