Viable

able to maintain a separate existence

Self-Reference

property of a system that contains all the levels below it

Homeostatis

stability of a system's internal environment, despite the system's having to cope with an unpredictable environment

Invariant

a factor in a complicated situation that is unaffected by all the changes surrounding it

Variety

a measure of complexity: the number of possible states of a system

The Law of Requisite Variety

only variety can absorb variety (Ashby's Law)

Attenuator

a device that reduces variety

Amplifier

a device that increases variety

Transducer

encodes or decodes a message whenever it crosses a system boundary - and therefore needs a different mode of expression

Oscillation

failing to settle down in homeostatic equilibrium, a dynamic system over-corrects itself continuously

Diagnosing the System for Organizations - Stafford Beer - John Wiley & Sons-