Isospin definition

A quantum number related to the number of charge states of a baryon or meson.

(particle physics) A quantum number used to distinguish the various states of electrical charge of a subatomic particle.

A vector quantity of quantum systems (especially subatomic particles) that is conserved in strong interactions and is used to characterize particles that are affected equally by the strong force but have other dissimilar properties, such as different electric charges. For example, protons and neutrons, which are indistinguishable with respect to strong force interactions, have the same isospin.