known vs preliminary

known

noun
  • Any fact or situation which is known or familiar. 

  • A constant or variable the value of which is already determined. 

adj
  • Accepted, familiar, researched. 

  • Identified as a specific type; famous, renowned. 

preliminary

adj
  • In preparation for the main matter; initial, introductory, preparatory. 

noun
  • Any of a series of sports events that determine the finalists 

  • A preparation for a main matter; an introduction. 

  • A relatively minor contest that precedes a major one, especially in boxing 

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