datum vs postulation

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. 

postulation

noun
  • Something self-evident that can be assumed as the basis of an argument. 

  • The act of postulating or something postulated. 

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