from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun The electrically neutral nucleon, a baryon composed of two down quarks and one up quark, which has a mass 1,839 times that of an electron, is stable when bound in an atomic nucleus, but has a mean lifetime of 886 seconds as a free particle. It is a basic component of all atomic nuclei except the protium isotope of hydrogen.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun physics A subatomic particle forming part of the nucleus of an atom and having no charge; it is a combination of an up quark and two down quarks

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

  • noun an elementary particle with 0 charge and mass about equal to a proton; enters into the structure of the atomic nucleus


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

[neutr(al) + –on.]


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  • A neutron walks into a bar and says "Hey, how much for a beer?"

    The bartender replies "For you, no charge."

    April 8, 2008

  • Haha! Cracks me up every time.

    An atom walks into a bar. "Hey, why so glum?" asks the bartender. "I think my electron left me," Atom says.

    "Are you sure?" says the bartender.

    "Yes. I'm positive."

    April 8, 2008

  • Hee! The Chem student in me loves these!

    April 8, 2008