negatron
/ˈnɛɡətrɒn/noun
1 Electronics. A valve with negative resistance, having an anode on one side of the cathode and a second anode and a control grid on the other side. Now historical.
2 Physics. An ordinary negatively charged electron (as distinct from a positron). Compare negaton. Now disused.
Origin
Early 20th century. From nega- + -tron.