quarterdeck vs superstructure

quarterdeck

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

superstructure

noun
  • Any structure built above the top full deck (FM 55-501). 

  • The sleepers and fastenings, in distinction from the roadbed. 

  • The social sphere of ideology which includes religion, art, politics, law and all traditional values. 

  • Any material structure or edifice built on something else; that which is raised on a foundation or basis. 

  • All that part of a building above the basement. 

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