duchess vs earl

duchess

noun
  • The female ruler of a duchy. 

  • The wife or widow of a duke. 

verb
  • to court or curry favour for political or business advantage; to flatter obsequiously. 

earl

noun
  • A British or Irish nobleman next in rank above a viscount and below a marquess; equivalent to a European count. A female using the style is termed a countess. 

  • Any of various nymphalid butterflies of the genus Tanaecia. Other butterflies in this genus are called counts and viscounts. 

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