datum vs preface

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. 

preface

noun
  • An introduction, or series of preliminary remarks. 

  • A title or epithet. 

  • The beginning or introductory portion that comes before the main text of a document or book. 

  • The prelude or introduction to the canon of the Mass. 

verb
  • To give a preface to. 

  • To introduce or make a comment before (the main point). 

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