Saturation
Also: actuator saturation, transistor saturation
A condition where increasing a command no longer produces the assumed proportional output.
In control it is an actuator limit; in a BJT it names a junction-bias region. Context must be stated because the models differ.
Example A controller asking for 120% duty receives only the allowed 100% output.
Common misconception Saturation is not additional control effort; the excess command cannot be delivered.