noun pi·on \ˈpī-ˌän\

Definition of pion

  1. :  a meson that is a combination of up and down quarks and antiquarks, that may be positive, negative, or neutral, and that has a mass about 270 times that of the electron


play \pī-ˈä-nik\ adjective

Origin and Etymology of pion

contraction of pi-meson

First Known Use: 1950

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