The process of holding constant a quantity such as speed, temperature, voltage, or position by means of an electronic or other system that automatically corrects errors by feeding back into the system the condition being regulated; regulation thus is based on feedback, whereas control is not.

The change in output voltage that occurs between no load and full load in a transformer, generator, or other source.

The difference between the maximum and minimum tube voltage drops within a specified range of anode current in a gas tube.