entity-relationship model (database, specification)
An approach to data modelling proposed by P. Chen in 1976. The model says that you divide your database in two logical parts, entities (e.g. "customer", "product") and relations ("buys", "pays for").
Entity-relationship diagrams can be used to represent a model.
["The entity-relationship model: toward a unified view of data", P.P. Chen, ACM Transactions on Database Systems 1:1 pp 9-36, 1976].
ERD Acronym! Holy fuck. Dig on this!