dame vs queen mother

dame

noun
  • A queen. 

  • Usually capitalized as Dame: a title equivalent to Sir for a female knight. 

  • In traditional pantomime: a melodramatic female often played by a man in drag. 

  • A matron at a school, especially Eton College. 

verb
  • To make a dame. 

queen mother

noun
  • A widowed queen consort (a queen dowager) whose son or daughter from that marriage is the reigning monarch. 

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