rheostat
A rheostat is a continuously variable ohmic resistor, i.e. a potentiometer.
The difference between a rheostat and a potentiometer is that the potentiometer uses three terminals and forms a voltage divider, whereas the rheostat uses only two terminals: An end terminal and the wiper contact. It is therefore an adjustable resistor whose current flow depends on the position of the wiper contact.
Rheostats can be made of carbon film or resistance wire deposited on a solid material such as cermet. Thus, all potentiometer designs are possible: layered, wire or helical rheostats. Rheostats are typically used at high power levels ranging from several watts to several hundred kilowatts. The resistance values can be in the ohm or kilo-ohm range.