datum vs lookout

datum

noun
  • A fact known from direct observation. 

  • 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. 

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

lookout

noun
  • A subject for observation; a prospect or view. 

  • A session of watching for an approaching enemy, police, etc. 

  • A person on watch for approaching enemy, police, danger, etc. 

  • A vantage point with a view of the surrounding area. 

  • A joist that extends in cantilever out from the exterior wall (or wall plate) of a building, supporting the roof sheathing and providing a nailing surface for the fascia boards. 

  • An observation window. 

  • One's perspective, outlook; hence, one's responsibility. (used with a possessive pronoun or a noun in a possessive form). 

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