etiquette vs propriety

etiquette

noun
  • The forms required by a good upbringing, or prescribed by authority, to be observed in social or official life; observance of the proprieties of rank and occasion; conventional decorum; ceremonial code of polite society. 

  • The customary behavior of members of a profession, business, law, or sports team towards each other. 

  • A label used to indicate that a letter is to be sent by airmail. 

  • 2012, July 15. Richard Williams in Guardian Unlimited, Tour de France 2012: Carpet tacks cannot force Bradley Wiggins off track 

propriety

noun
  • Correctness in behaviour and morals; good manners, seemliness. 

  • The fact of possessing something; ownership. 

  • Suitability, fitness; the quality of being appropriate. 

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