Any particle that obeys Fermi-Dirac statistics and is subject to the Pauli exclusion principle.
In physics, a subatomic particle whose spin can only take values that are half-integers, such as ˝ or 3/2. Fermions may be classified as leptons, such as the electron, and baryons, such as the proton and neutron. All elementary particles are either fermions or bosons.
The exclusion principle, formulated by Austrian–US physicist Wolfgang Pauli 1925, asserts that no two fermions in the same system (such as an atom) can possess the same position, energy state, spin, or other quantized property.