Definition of fermion in US English:



  • A subatomic particle, such as a nucleon, which has half-integral spin and follows the statistical description given by Fermi and Dirac.

    • ‘In addition to electrons, the Pauli exclusion principle applies to all sub-atomic particles with half-integral spins, known as fermions, such as neutrons and protons.’
    • ‘What happens next in these so-called quantum-degenerate gases depends on whether the atoms are bosons or fermions.’
    • ‘But if supersymmetry were unbroken, fermions and bosons would be exactly matched in the Universe, and that's not the way things are.’
    • ‘But physicists have since extended their work to create Fermi gases made from atoms that are fermions - particles with half-integer spin.’
    • ‘Well, what we find experimentally is that the quasiparticles are almost always fermions or bosons.’


1940s: from the name of Fermi, Enrico + -on.