Nonode

A nonode is an electronic device having nine active electrodes. The term most commonly applies to a seven-grid vacuum tube, also sometimes called an enneode. An example was the EQ80, which was used as an FM Quadrature Detector.

There was also an interesting concept implemented with nonodes. The idea was that every valve in the set was the same type, and connecting up its electrodes differently enabled it to do the full range of jobs required in a radio. The point was to solve the spares & serviceability problem, with nonode equipment far less quantity of spares could be far more useful. AFAIK these never saw widespread use though.