corsair vs robber

corsair

noun
  • A privateer or pirate in general. 

  • A French privateer, especially from the port of Saint-Malo. 

  • A nocturnal assassin bug of the genus Rasahus, found in the southern USA. 

  • The ship of privateers or pirates, especially of French nationality. 

  • A Californian market fish (Sebastes rosaceus). 

robber

noun
  • A person who robs. 

  • An animal who robs. 

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