'Datum line' definitions:

Definition of 'Datum line'

From: GCIDE
  • Datum \Da"tum\, n.; pl. Data. [L. See 2d Date.]
  • 1. Something given or admitted; a fact or principle granted; that upon which an inference or an argument is based; -- used chiefly in the plural. [1913 Webster]
  • Any writer, therefore, who . . . furnishes us with data sufficient to determine the time in which he wrote. --Priestley. [1913 Webster]
  • 2. a single piece of information; a fact; especially a piece of information obtained by observation or experiment; -- used mostly in the plural. [PJC]
  • 3. pl. (Math.) The quantities or relations which are assumed to be given in any problem. [1913 Webster]
  • 4. (Surveying) a point, line, or level surface used as a reference in measuring elevations. --RHUD [PJC]
  • Datum line (Surv.), the horizontal or base line, from which the heights of points are reckoned or measured, as in the plan of a railway, etc. [1913 Webster]