Tauon

n. (Physics) tau lepton, tau, negatively charged lepton having a mass almost 3500 times that of the electron (discovered by Martin Lewis Perl)

The tau lepton (often called the tau, tau particle, or occasionally the tauon, symbol ) is a negatively charged elementary particle with a lifetime of 2.90×10−13 seconds and a mass of 1777 MeV/c2 (compared to 938 MeV/c2 for protons and 0.511 MeV/c2 for electrons). It has an associated antiparticle (the anti-tau) and neutrinos (the tau neutrino and tau antineutrino).
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Noun
1. a lepton of very great mass
(synonym) tau-minus particle
(hypernym) lepton

n. tauon

A cousin of an electron but heavier than the muon; a tauon is a negatively charged lepton . It is 3560 times heavier than an electron with mass 1784 Mev/c2; it is short lived with a mean life of 3.4 x 10-13 seconds to decay by one of various modes. There is an antimatter positive tau particle.