see Resistor, Variable.

A variable resistor. A device which does not have a linear resistance characteristic.

a component that changes resistance with the amount of voltage impressed across it

a device specifically designed to have a well-defined voltage-dependent resistance

an electronic component designed to protect circuits against excessive voltage

a resistor that has a resistance that varies with temperature

a resistor whose resistance depends on the applied voltage

a two-electrode active or passive semiconductor device with a voltage dependent nonlinear resistance which falls significantly as the voltage is increased

a type of resistor with a significantly non-ohmic current -voltage characteristic

a very rugged voltage clamping device capable of absorbing very large currents without damage

a voltage dependent, nonlinear device that has an electrical behavior similar to back-to-back Zener diodes

A voltage-dependent variable resistor. Normally used to protect sensitive equipment from power spikes or lightning strikes by shunting the energy to ground.

A semiconductor device with a voltage dependent resistance that drops markedly as the applied voltage is increased.

A semiconductor device with voltage-sensitive resistance, commonly used as a lightning arrester. Overvoltages can be passed quickly, but operating voltages have no effect.

A varistor is an electronic component with a significant non-ohmic current-voltage characteristic. The name is a portmanteau of variable resistor. Varistors are often used to protect circuits against excessive transient voltages by incorporating them into the circuit in such a way that, when triggered, they will shunt the current created by the high voltage away from the sensitive components.