(set theory) A diagram representing some sets by contours of closed shapes, such as circles or ellipses (and sometimes also the universal set as a rectangle enclosing all of these shapes), and indicating the relationships between the sets: by overlapping the shapes to show that the corresponding sets have a non-empty intersection, and by possibly (but not necessarily) enclosing all of the sets (which are proper subsets of the universal set) within a universal set (represented typically by a rectangle); such that the total number of simply connected regions is 2ⁿ, where n is the number of depicted sets which are proper subsets of the universal set.

(physics, chemistry) A graph, with axes representing temperature and pressure, showing the equilibrium conditions for a given substance to be a solid, liquid or gas.

(physics) A pictorial representation of the interactions of subatomic particles, showing their paths in space and time as lines, and their interactions as points where lines meet.

A schematic representation of the components of an electrical device showing how electrical wiring must be connected.

An entity-relationship diagram; a specialized (usually dynamic) chart that illustrates the relationships between entities in a database, using a specific set of database-specific symbols.

A pictorial representation of a system or process in which subsystems or other components are represented by geometric shapes joined by lines or arrows

plural of Feynman diagram

A diagram used in quality management to display a detailed list of causes and effects of a problem and thus to decipher the root cause of a problem.

(software engineering) A type of static structure diagram that describes the structure of a system by showing the system's classes, their attributes, and the relationships between the classes.

A diagram in the field of logic. / Any non-spatial, abstract diagram. / Any schematic display of the logical relationships of project activities.