The Collaborative International Dictionary
tau-minus particle
lepton \lepton\ n. (Physics) an elementary particle that participates in weak interactions but does not participate in the strong interaction; it has a baryon number of 0. Some known leptons are the electron, the negative muon, the tau-minus particle, and the neutrinos associated with each of these particles.
WordNet
tau-minus particle
n. a lepton of very great mass [syn: tauon]