"A system is an organized collection of parts (or subsystems) that are highly integrated to accomplish an overall goal."1
Organized means that the elements or parts of a system are not randomly positioned.
Collection of parts means that a system is complex - various parts make up a system.
Highly integrated means that system parts are or should be interconnected. The destruction of such connectedness may break up the system.
(1) Carter McNamara, Field Guide to Consulting & Org. Development
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