(1) A rule that limits the values that can be inserted, deleted, or updated in a table. See also check constraint, primary key, referential constraint, unique constraint, unique key, foreign key, informational constraint.
(2) A place in the system where contention for a resource is affecting performance.
(3) See threshold.
(4) A semantic condition or restriction. Certain constraints are predefined in the UML, others may be user defined. Constraints are one of three extensibility mechanisms in UML. See also tagged value, comment.
(5) A limit to set controls on the start and finish dates on task elements of the project, such as start-no-earlier-than or finish-no-later-than.
(6) In lexical analysis, a morphotactics rule that accurately processes compound words using dictionaries of word formation elements.