(1) A collection of assertions that describe the allowed states that a managed object can assume. An assertion can be a precondition, a postcondition, or an invariant. In practice, the behavior is often an informal description of the semantics of attributes, operations, and notifications.
(2) The way in which managed objects, name bindings, attributes, notifications, and operations interact with the actual resources that they model and with each other.
(3) In object-oriented programming, the functionality embodied within a method.
(4) The observable effects of an operation or event, including its results.