1 [data models] An abstraction of reality used to represent objects, processes, or events.
2 [modeling] A set of rules and procedures for representing a phenomenon or predicting an outcome.
3 [data models] A data representation of reality, such as the vector data model.
4 [ESRI software] In geoprocessing in ArcGIS, one process or a sequence of processes connected together, that is created in ModelBuilder.