datum vs refutation

datum

noun
  • A premise from which conclusions are drawn. 

  • A floating reference point, or SLDMB, used to evaluate surface currents in a body of water. Often employed by coastal search and rescue. 

  • A fixed reference point or set of reference points which precisely define a system of measurement or a coordinate system. 

  • A fact known from direct observation. 

verb
  • To provide missing data points by using a mathematical model to extrapolate values that are outside the range of a measuring device. 

refutation

noun
  • A vocal answer to an attack on one's assertions. 

  • An act of refuting or disproving; the disproving of an argument, opinion, testimony, doctrine or theory by argument or countervailing proof; evidence of falseness. 

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