In irreversible thermodynamics, it is a non-linear system capable of assimilating large reserves of energy from the environment and converting them into increasing structural complexity, thus maintaining its integrity while it is far-from-equilibrium. Existing in a far-from-equilibrium state, such a thermodynamically open system shows spontaneous internal fluctuations that can be amplified to the point that they change the system’s behavior qualitatively (i.e., it moves to a new state).
See Bifurcation, Complexity, Instability, Irreversible thermodynamics, Quantitative and qualitative change, Non-linear dynamical systems, Non-linear dynamics, Open system, Quantitative and qualitative change, Self-organization, Transition