|Definition:|| particle with half-integer spin quantum number, i.e. 1/2, 3/2, ...|
NOTE 1 Fermions undergo Fermi-Dirac statistics and obey the Pauli exclusion principle, which asserts that only a single particle can be assigned to a given quantum state.
NOTE 2 Fermions are e.g. the electron, all neutrinos and quarks, and all particles constituted from an odd number of fermions (e.g., proton, neutron, helium nucleus 3He).