house martin vs sailor

house martin

noun
  • A migratory passerine bird of the swallow family, genus Delichon 

  • The common house martin (Delichon urbicum). 

sailor

noun
  • Any of various nymphalid butterflies of the genera Neptis, Pseudoneptis and Phaedyma, having white markings on a dark base and commonly flying by gliding. 

  • A member of the crew of a vessel; a mariner; a common seaman. 

  • A person who sails sailing boats as a sport or recreation. 

  • A person in the business of navigating ships or other vessels 

  • Someone knowledgeable in the practical management of ships. 

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