# muon

> English word · Noun · IPA /ˈmjuːɒn/ · frequency rank #61,653

## Definitions
1. An unstable elementary particle in the lepton family, having similar properties to the electron but with a mass 207 times greater.

## 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.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/muon