System (noun)

1. A set of things working together as parts of a mechanism or an interconnecting network.
2. A complex whole made up of interconnected parts.
3. A set of principles or procedures according to which something is done.
4. A set of connected things or parts forming a complex whole.

Origin:

Late middle english, from latin systema, from greek, from systēma, from syn- + histanai to cause to stand.

Examples:

1. The human body is a complex system.
2. The solar system is made up of planets and stars.
3. The new computer system is very efficient.
4. The system of government in this country is a democracy.
5. The transportation system in this city is very good.