plural data 1. facts, numbers, letters, symbols, line graphics, imagery, or alphanumeric information that refer to or describe an object, idea, condition, situation, or other factor —note data connote basic elements of information that can be analyzed, processed, stored, or manipulated by a computer 2. geodetics a reference surface consisting of five quantities: the latitude and longitude of an initial point, the azimuth of a line from this point, and two constants necessary to define the reference spheroid —note 1. a datum forms the basis for the computation of horizontal control surveys in which the curvature of the earth is considered —note 2. the corresponding datum is the basis for a planar coordinate system, e.g., the North American datum for 1983 (NAD83) is the datum for map projections and coordinates in all of North America —synonym horizontal control datum, horizontal datum, horizontal geodetic datum 3. a level surface to which elevations are referred, usually but not always mean sea level —synonym vertical datum, vertical controlThis definition last updated 10/25/2008