parapet vs quarterdeck

parapet

noun
  • Part of a perimeter that extends above the roof. 

  • A fortification consisting of a wall. 

  • A low protective wall. 

  • Hyponym: balustrade 

quarterdeck

noun
  • The aft part of the upper deck of a ship; normally reserved for officers 

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