Real Dictionary

system
a group or combination of interrelated, interdependent, or interacting elements forming a collective entity; a methodical or coordinated assemblage of parts, facts, concepts, etc [...]
the study of living organisms, including their structure, functioning, evolution, distribution, and interrelationships [...]
countable noun: A system is a set of devices powered by electricity, for example a computer or an alarm.
countable noun: A system is a way of working, organizing, or doing something which follows a fixed plan or set of rules. You can use system to refer to an organization or institution that is organized in this way.