any particle that obeys Fermi-Dirac statistics and is subject to the Pauli exclusion principle
Any elementary or composite particle that has half-integer spin and thus obeys Fermi–Dirac statistics and the Pauli exclusion principle (equivalently, a particle for which the wavefunction of any system of identical such particles changes sign whenever two are swapped); a baryon, a lepton or a quark;, (slightly more loosely) any such particle or any composite particle composed of fermions.