from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An elementary particle in the lepton family (not a meson), having a mass 209 times that of the electron, a negative electric charge, and a mean lifetime of 2.2 × 10-6 seconds. Also called mu meson. See Table at subatomic particle.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An unstable elementary particle in the lepton family, having similar properties to the electron but with a mass 209 times greater.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. an elementary particle with a negative charge and a half-life of 2 microsecond; decays to electron and neutrino and antineutrino
Short for mu meson.(American Heritage® Dictionary of the English Language, Fourth Edition)
Contraction of mu-meson (the particle has now been recategorised as a lepton). (Wiktionary)