an electron tube in which the flow of electrons from the cathode to one or more anodes is controlled by an externally applied magnetic field: used to generate alternating currents at microwave frequencies
Origin:
magne(t) + (elec)tron
See magnetron in American Heritage Dictionary 4
noun
A microwave tube in which electrons generated from a heated cathode are affected by magnetic and electric fields in such a way as to produce microwave radiation used in radar and in microwave ovens.