maid vs mother superior

maid

noun
  • A female servant or cleaner (short for maidservant). 

  • A girl or an unmarried young woman; maiden. 

mother superior

noun
  • A nun in charge of a priory or convent; either a prioress or an abbess. 

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