[iso.spin] n (1961): a quantum characteristic of a group of closely related subatomic particles (as a proton and a neutron) handled mathematically like ordinary spin with the possible orientations in a hypothetical space specifying the number of particles of differing electric charge comprising the group--called also isotopic spin
ISOSPIN
Meaning of ISOSPIN in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012