steady state

Main Entry: steady state
Function: noun
1 : a state or condition of a system or process (as one of the energy states of an atom) that does not change in time
2 : a state of physiological equilibrium especially in connection with a specified metabolic relation or activity

steady state stead·y state (stěd'ē)
n.

1. A state obtained in moderate muscular exercise when the removal of lactic acid by oxidation keeps pace with its production.

2. A condition in which the formation of substances keeps pace with their destruction so that all volumes, concentrations, pressures, and flows remain constant.

3. A stable condition that does not change over time or in which change in one direction is continually balanced by change in another.