battleship vs gunship

battleship

noun
  • A large capital warship displacing thousands to tens of thousands of tons, heavily armoured and armed with large-caliber guns; now obsolescent and replaced by smaller vessels with guided missiles. 

  • A guessing game played on grid paper; see Battleship (game). 

  • A non-functional rocket stage, used for configuration and integration tests. 

gunship

noun
  • A ship equipped with heavy artillery. 

  • An armed helicopter tasked to attack the enemy. 

  • A transport airplane equipped with large calibre guns typical of armoured fighting vehicles 

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