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pion

[pahy-on]
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noun Physics.
  1. the first meson to be discovered: it has spin 0 and may be positively or negatively charged or neutral; charged pions decay into a muon and a neutrino or antineutrino. Symbol: π

Origin of pion

First recorded in 1950–55; pi (meson) + -on1
Also called pi meson.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Examples from the Web for pion

Historical Examples

  • Do not forget next week at the home of Endora, on the Mountain of Pion.

    Saronia

    Richard Short

  • I refer to the pion pine, of which there are several species.

    North America

    Israel C. Russell

  • But he turned and scrambled up a rocky bank into the pion woods that border the benches of the Meteetsee.

    The Biography of a Grizzly

    Ernest Seton-Thompson

  • This heres the Wagon Tire House, returned its proprietor, rising and shaking the pion slivers from her checked apron.

  • The dense forest consists of pion pine, juniper, Douglas fir, and western yellow pine.


British Dictionary definitions for pion

pion

pi meson

noun
  1. physics a meson having a positive or negative charge and a rest mass 273.13 times that of the electron, or no charge and a rest mass 264.14 times that of the electron

Word Origin

C20: from Greek letter pi 1 + on
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for pion

n.

1951, from Greek letter pi + -on.

Online Etymology Dictionary, © 2010 Douglas Harper

pion in Science

pion

[pīŏn′]
  1. A meson occurring either in a neutral form with a mass 264 times that of an electron and a mean lifetime of 8.4 X 10-17 seconds or in a positively or negatively charged form with a mass 273 times that of an electron and a mean lifetime of 2.6 X 10-8 seconds. The pion was once believed to be the particle that mediates the strong force, which holds nucleons together in the nucleus; it is now believed that the gluon is the mediator particle. Pions do interact with nucleons, however, and are able to transform neutrons into protons and vice versa. Also called pi-meson See Table at subatomic particle.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.