The INCOSE Fellows’ Initiative on System and Systems Engineering Definitions was established in 2016, to review current INCOSE definitions of SYSTEM and SYSTEMS ENGINEERING, and to recommend any changes necessary to align the definitions to current practice and to the aspirations of INCOSE’s 2025 Vision.  

This website presents the approved final output from the initiative in on-line form, as a set of linked web pages.
The definitions were approved in 2019, and the formal published document version of the new definitions was launched by INCOSE at the International Symposium in Summer 2019.

The final definitions take into account the extensive comments received during the review of the previous draft in September 2018. The review was open to all INCOSE members, and attracted over 350 individual comments and suggestions.

The three key recommendations – for definitions of systems engineering, engineered system, and a general definition of system – are presented here, with a very brief contextual explanation. Other pages provide more explanation of these definitions, and also define other specific system types and categories that are important for the systems engineering community.

The Three Essential Definitions

Systems Engineering Definition

Systems Engineering is a transdisciplinary and integrative approach to enable the successful realization, use, and retirement of engineered systems, using systems principles and concepts, and scientific, technological, and management methods.

We use the terms “engineering” and “engineered” in their widest sense: “the action of working artfully to bring something about”. “Engineered systems” may be composed of any or all of people, products, services, information, processes, and natural elements. 

Engineered System Definition

An engineered system is a system designed or adapted to interact with an anticipated operational environment to achieve one or more intended purposes while complying with applicable constraints.

Thus, an “engineered system” is a system – not necessarily a technological one – which has been or will be “systems engineered” for a purpose.  

Most General “System” Definition

A system is an arrangement of parts or elements that together exhibit behaviour or meaning that the individual constituents do not.

Systems can be either physical or conceptual, or a combination of both.

Systems in the physical universe are composed of matter and energy, may embody information encoded in matter-energy carriers, and exhibit observable behaviour.

Conceptual systems are abstract systems of pure information, and do not directly exhibit behaviour, but exhibit “meaning”. In both cases, the system’s properties (as a whole) result, or emerge from:

the parts or elements and their individual properties; AND

the relationships and interactions between and among the parts, the system and its environment.

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