Meson definition

Any of a family of subatomic particles that are composed of a quark and an antiquark. Their masses are generally intermediate between leptons and baryons, and they can have positive, negative, or neutral charge. Mesons form a subclass of hadrons and include the kaon, pion and J/psi particles. Mesons were originally believed to be the particles that mediated the strong nuclear force, but it has since been shown that the gluon mediates this force.

(particle physics) Any of a group of subatomic particles that are both hadrons and bosons, including the pion and kaon.

(rare except entomology) The mesial plane dividing the body into similar right and left halves.

Any of a class of subatomic particles that are both hadrons and bosons, are composed of a quark and an antiquark, participate in strong interactions, and have masses generally intermediate between those of leptons and baryons.