A group of interacting or interrelated entities (called components) that form a unified whole which is:
System consists of components and properties. The full set of properties at current moment is called a System State.
Description of a System behaviour in response to or correlation with its properties is provided by a System Model.
Depending on whether a System has properties changing over time it can be a Static System or Dynamic System.
Human / Science / Formal Science / Mathematics
[ Components ] [ Properties ] [ System State ]
[ Static System ] [ Dynamic System ]
[ Model ] [ Variable ] [ Constant ]