cavity magnetron referred as diode

I read abt cavity magnetron from the book "Electronic communication system" by Kennedy

It mentions as follows:

"The cavity magnetron is a diode usually of cylindrical construction"

How can the cavity magnetron be described as diode?

Electrically it is a diode. There is a heated cathode and an anode. In the absence of the magnetic field, it would act just like a power rectifier.

i agree flatulent.
I just add an opinion:
Some time, reading technical pubblication, the reader must be driven by the intuition.
In this case the intuition suggest that the term "diode" call for the type of power supply: DC rather tha AC.
The Magnetron still remain a power RF oscillator.