datum vs tract

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. 

tract

noun
  • A commentator's view or perspective on a subject. 

  • Part of the proper of the liturgical celebration of the Eucharist for many Christian denominations, used instead of the alleluia during Lenten or pre-Lenten seasons, in a Requiem Mass, and on a few other penitential occasions. 

  • A series of connected body organs, such as the digestive tract. 

  • Continued or protracted duration, length, extent 

  • A brief treatise or discourse on a subject. 

  • An area or expanse. 

  • A small booklet such as a pamphlet, often for promotional or informational uses. 

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