rheostat

This term is primarily used in technical, engineering, and electrical contexts. It describes a specific type of variable resistor designed to handle higher currents than a potentiometer, though the two are often confused in casual conversation. In a professional setting, using "rheostat" specifically implies the control of power or current flow rather than the measurement of voltage.

Because it is a physical piece of hardware, it follows standard countability rules for equipment. It is not an abstract concept or a mass noun, meaning it is used with singular and plural articles and numbers.