(1) one or more organizations sharing a definite mission, goals, and objectives to offer an output such as a product or service. (ISO 2000)
(2) An organization (or cross organizational entity) supporting a defined business scope and mission that includes interdependent resources (people, organizations and technologies) that must coordinate their functions and share information in support of a common mission (or set of related missions). (CIO Council 1999)
(3) the term enterprise can be defined in one of two ways. The first is when the entity being considered is tightly bounded and directed by a single executive function. The second is when organizational boundaries are less well defined and where there may be multiple owners in terms of direction of the resources being employed. The common factor is that both entities exist to achieve specified outcomes. (MOD 2004)
(1) ISO. 2000. Industrial Automation Systems -- Requirements for Enterprise-Reference Architectures and Methodologies. Geneva, Switzerland: International Organization for Standardization (ISO), ISO 15704:2000.
(2) CIO Council. 1999. Federal Enterprise Architecture Framework (FEAF). Washington, DC: Chief Information Officer (CIO) Council.
(3) MOD. 2004. Ministry of Defence Architecture Framework (MODAF), version 2. UK: U.K. Ministry of Defence.
Discussion as to why this is the "consensus" definition for the SEBoK.