Particle Physics any of a class of subatomic particles that obey the Pauli exclusion principle and have fractional spin, including the leptons, quarks, and baryons
Origin of fermionafter Fermi + -on
Any of a class of particles having a spin that is half an odd integer and obeying the exclusion principle, by which no more than one identical particle may occupy the same quantum state. The fermions include the baryons, quarks, and leptons.
Origin of fermionAfterEnrico Fermi
From Enrico Fermi (Italian-American physicist) + -on.