muon

American  

[myoo-on] / ˈmyu ɒn /

noun

Physics.

1. a lepton similar in most respects to the electron except that it is unstable, it may be positively charged, and its mass is approximately 207 times greater; the positively charged muon is the antiparticle of the negatively charged muon. μ

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muon British  

/ ˈmjuːɒn, mjuːˈɒnɪk /

noun

1. a positive or negative elementary particle with a mass 207 times that of an electron and spin 1/ 2 . It was originally called the mu meson but is now classified as a lepton

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muon Scientific  

/ myo̅o̅′ŏn′ /

1. An elementary particle in the lepton family having a mass 209 times that of the electron, a negative electric charge, and a mean lifetime of 2.2 × 10 ^{- 6} seconds. The muon was originally called the mu-meson and was once thought to be a meson.

2. See Table at subatomic particle

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Other Word Forms

• muonic adjective

Etymology

Origin of muon

1950–55; by shortening of mu meson; mu, -on ¹

Example Sentences

The project is designed to look for an extremely rare event in which muonium, a short lived system made of a positive muon bound to an electron, spontaneously transforms into antimuonium, its antimatter counterpart.

From Science Daily • Feb. 2, 2026

"In practice, what we did is produce muon neutrinos and if a sterile neutrino were to exist, we would see an appearance of electron neutrinos."

From Science Daily • Jan. 12, 2026

SNO+ is a successor to the earlier SNO experiment, which demonstrated that neutrinos switch between three forms known as electron, muon, and tau neutrinos as they travel from the Sun to Earth.

From Science Daily • Dec. 12, 2025

So the muon collider could be much smaller and, hence, cheaper.

From Science Magazine • Mar. 27, 2024

The world's ultimate pragmatist just shrugs and says: "NhUng gi minh mong it khi nao no jcay ra. Nhung gi minh khong muon thi no lai cti den."

From "Counting by 7s" by Holly Goldberg Sloan