The story
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A mass analyzer consisting of an outer barrel-like electrode and a coaxial inner spindle-like electrode that traps ions in an orbital motion around the spindle. The image current from the trapped ions is detected and converted to a mass spectrum using the Fourier transform of the frequency signal. Full definition →
Etymology from Wiktionary, CC BY-SA 4.0.