An Etymological Dictionary of Astronomy and Astrophysics

A nuclear particle with a mass intermediate between that of a proton and an electron, which is believed to be responsible for the strong nuclear force. In contrast to the case of baryons or leptons, meson number is not conserved: like photons, mesons can be created or destroyed in arbitrary numbers. Their charge can be positive, negative, or zero.

See also: From mes-, meso-, from Gk. mesos “middle,” akin to L. medius, Pers. miyân, → medium, → middle,

• -on a suffix used in the names of subatomic particles.