mystery vs nth

mystery

noun
  • Someone or something with an obscure or puzzling nature. 

  • Something secret or unexplainable; an unknown. 

  • A religious truth not understandable by the application of human reason alone (without divine aid). 

  • A particular event or series of events in the life of Christ. 

  • A sacrament. 

  • A secret religious celebration, admission to which was usually through initiation. 

  • A craft, art or trade; specifically a guild of craftsmen. 

nth

noun
  • The item in a relatively large but unspecified position in a series. 

  • The item at position n in a sequence. 

adj
  • Occurring at a relatively large but unspecified position in a series. 

  • Occurring at position n in a sequence. 

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