datum: Meaning and Definition of

da•tum

1. a single piece of information, as a fact, statistic, or code; an item of data.
1. any fact assumed to be a matter of direct observation.
2. any proposition assumed or given, from which conclusions may be drawn.
3. Also calledthe object of knowledge as presented to the mind. Cf. ideatum.
4. any level surface, line, or point used as a reference in measuring elevations.
5. a basis for horizontal control surveys, consisting of the longitude and latitude of a certain point, the azimuth of a certain line from this point, and two constants used in defining the terrestrial spheroid.