The Collaborative International Dictionary
Rheotome
Rheotome \Rhe"o*tome\ (r[=e]"[-o]*t[=o]m), n. [Gr. "rei^n to
flow + te`mnein to cut.] (Elec.)
An instrument which periodically or otherwise interrupts an
electric current.
--Wheatstone.
Wiktionary
rheotome
n. Any instrument that interrupts an electric current.