folk vs unwritten

folk

adj
  • Believed or transmitted by the common people; not academically correct or rigorous. 

  • Of or pertaining to common people as opposed to ruling classes or elites. 

  • Of or pertaining to the inhabitants of a land, their culture, tradition, or history. 

  • Of or related to local building materials and styles. 

noun
  • People in general. 

  • The inhabitants of a region, especially the native inhabitants. 

  • One’s relatives, especially one’s parents. 

  • A particular group of people. 

unwritten

adj
  • Implicit or understood but not formally articulated. 

  • Not written. 

  • Oral or otherwise communicated without writing. 

  • Containing no writing; blank. 

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