An unstable elementary particle in the lepton family, having similar properties to the electron but with a mass 207 times greater.
Pronounced as (IPA)
/ˈmjuːɒn/
Etymology
Contraction of the earlier term mu-meson; the particle has now been recategorised as a lepton. Coined by Italian physicist Enrico Fermi in 1951 in his book Elementary Particles.