rheostat

noun

device that adjusts magnitude of current in a circuit by changing length

Wiktionary

Pronunciation: /ˈɹiː.ə.stat/ / /-stæt/ / /-əʊ̯-/

noun

Etymology: Etymology tree Proto-Indo-European *ser-? Proto-Indo-European *srew- Proto-Indo-European *sréweti Proto-Hellenic *hréwō Ancient Greek ῥέω (rhéō) English rheo- English -stat English rheostat From rheo- + -stat.

An electrical resistor, with two terminals, whose resistance is continuously variable by moving a knob or slider.