an electron tube that uses electric fields and resonant cavities to bunch electrons from a uniform stream, used as an oscillator, amplifier, etc. in ultrahigh frequency circuits, and esp. as a generator and amplifier of microwaves
< Gr klys- (see clyster) + (elec)tron
See klystron in American Heritage Dictionary 4
An electron tube used to amplify or generate ultrahigh frequency by means of velocity modulation.