Definition of "overvoltage"

(physics) The difference between the electric potential of an electrode or cell under the passage of a current and the thermodynamic value of the electrode or cell potential in the absence of electrolysis; overpotential.  examples

The hazardous condition that occurs when the voltage in a circuit is raised above that for which it was designed.  examples

To raise the voltage of a circuit beyond that for which it was designed.  examples