Definition of "meson" [‖Mes•on]

• Any of a family of subatomic particles that participate in strong interactions, are composed of a quark and an antiquark, and have masses generally intermediate between leptons and baryons. See Table at subatomic particle. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "A new period in meson research began about three years ago."
• "The latter meson is identical with the one whose existence in cosmic rays had been previously established by American researchers."
• "The mass of the (p) - meson is said to be 286 times greater than the mass of the electron, and that of the µ-meson 216 times greater."