prolegomenon vs significant

prolegomenon

noun
  • A prefatory discussion; a formal essay or critical discussion serving to introduce and interpret an extended work. 

significant

noun
  • That which has significance; a sign; a token; a symbol. 

adj
  • Reasonably large in number or amount. 

  • Having a low probability of occurring by chance (for example, having high correlation and thus likely to be related). 

  • Having a covert or hidden meaning. 

  • Having a noticeable or major effect. 

  • Signifying something; carrying meaning. 

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