noun. The negatively charged lepton that belongs to the second generation of elementary fermions and has a mass 207 times that of an electron and a mean lifetime of 2.2 × 10⁻⁶ second.

noun. An unstable elementary particle in the lepton family, having similar properties to the electron but with a mass 209 times greater.

noun. an elementary particle with a negative charge and a half-life of 2 microsecond; decays to electron and neutrino and antineutrino

"It was then realized that the particle found by Anderson could not be the meson of strong interactions, since it interacted far too little with matter, and it was then shown that this particle, now called the muon, is a heavy cousin of the electron."

lepton  

antimatter  energy-dispersive  gravitonic  holesare  hyperfine