1 [coordinate systems] A fixed reference point in a coordinate system from which all other points are calculated, usually represented by the coordinates (0,0) in a planar coordinate system and (0,0,0) in a three-dimensional system. The center of a projection is not always its origin.
2 [ESRI software] The primary object in a relationship, such as a feature class containing points where measurements are taken. The measurements are stored in another table.
3 [ESRI software] In a network in ArcInfo Workstation, the beginning of a path.
4 [ESRI software] In ArcGIS Network Analyst, a network location used in origin-destination cost matrix analysis that specifies a starting location.