a visual representation of the relationship between bits of data or information. Typically how one bit relates to, works with, is next in line to, or is driven by something else. A diagram of a set of roads is called a road map. A diagram of the floor of a building is called a floor map. A diagram of how people work together is called a organization chart.
An informal, graphical picture of some set of entities and some relations between them. Contrast with model.
A diagram is a graphical presentation of a compilation of model elements, rendered as a graph of shapes connected by paths. Comprehension resides mainly in the topology, not in the size or placement of the symbols.