pion

Meanings

1. 1
   noun

   any of three unstable spin-zero mesons, positively charged, negatively charged, or neutral, made from combinations of up and down quarks and antiquarks

   The detector identified a charged pion from its curved track and subsequent decay.

A contraction of pi-meson, first recorded in English around 1950. Pi is the name of the Greek letter used in the particles' symbols, and -on is the particle-name suffix also seen in proton and neutron.

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