meson /ˈmiːzɒn/noun 2/ˈmɛs.ɒn/ noun 1forms 1 noun2 •An elementary particle that is composed of a quark and an antiquark, such as a kaon or pion. (Mesons composed of rarer quarks are much heavier.) •(no longer used) A member of a group of subatomic particles having a mass intermediate between electrons and protons. (The most easily detected mesons fit this definition.) meson /ˈmɛs.ɒn/ noun1 •The mesial plane dividing the body into similar right and left halves. formsmesons
