Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

  • n. A semistable meson produced either in a neutral form with a mass 264 times that of an electron and a mean lifetime of 8.4 × 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 × 10-8 seconds. Also called pi meson. See Table at subatomic particle.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Any of three semistable mesons, having positive, negative or neutral charge, composed of up and down quarks/antiquarks.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a meson involved in holding the nucleus together; produced as the result of high-energy particle collision

Etymologies

Contraction of pi meson.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From pi + -on, as alteration of pi-meson. (Wiktionary)

Examples

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