muon

noun

mu·​on ˈmyü-ˌän 

: an unstable lepton that is common in the cosmic radiation near the earth's surface, has a mass about 207 times the mass of the electron, and exists in negative and positive forms

muonic

myü-ˈä-nik 

adjective

Examples of muon in a Sentence

Recent Examples on the Web

The only viable explanation is that an even higher-energy particle — a more stable one — must have struck the upper atmosphere of the Earth and produced a particle shower, where those decaying particles led to the presence of these muons. —Big Think, 30 Jan. 2026

There might exist, for instance, an unstable type of dark matter particle that leaves its mark by occasionally arising and immediately decaying into an excessive number of muon-antimuon pairs. —Quanta Magazine, 26 Jan. 2026

Axani’s CosmicWatch device detects one of these secondary particles, called muons. —Chris Young, Interesting Engineering, 8 Jan. 2026

Cosmic rays batter Earth's atmosphere constantly, interacting with molecules of air and producing showers of exotic particles such as muons, high energy neutrons and positrons. —Tereza Pultarova, Space.com, 3 Dec. 2025

Word History

Etymology

contraction of earlier mu-meson, from mu

First Known Use

1951, in the meaning defined above