fermion

American  

[fur-mee-on] / ˈfɜr miˌɒn /

noun

Physics.

1. any particle that obeys the exclusion principle and Fermi-Dirac statistics; fermions have spins that are half an odd integer: 1/2, 3/2, 5/2, …

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fermion British  

/ ˈfɜːmɪˌɒn /

noun

1. any of a group of elementary particles, such as a nucleon, that has half-integral spin and obeys Fermi-Dirac statistics Compare boson

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fermion Scientific  

/ fûr′mē-ŏn′,fĕr′- /

1. An elementary or composite particle, such as an electron, quark, or proton, whose spin is an integer multiple of 1/2. Fermions act on each other by exchanging bosons and are subject to the Pauli exclusion principle, which requires that no two fermions be in the same quantum state. Fermions are named after the physicist Enrico Fermi, who along with Paul Dirac developed quantum statistical models of their behavior.

2. Compare boson

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Other Word Forms

• fermionic
  adjective

Etymology

Origin of fermion

First recorded in 1945–50; fermi + (mes)on

Compare meaning

How does fermion compare to similar and commonly confused words? Explore the most common comparisons:

• boson vs. fermion

Example Sentences

Since the 1970s, scientists have predicted the existence of a third type of particle known as an anyon, which falls somewhere between a boson and a fermion.

From Science Daily • May 9, 2026

Supersymmetry hypothesizes an as-yet-undiscovered boson partner for every fermion, and a fermion partner for each boson.

From New York Times • May 8, 2023

This idea predicts fermion dark matter particles that have some kind of interaction with one another—a self-interaction—beyond gravity.

From Scientific American • Apr. 4, 2022

Massive Dirac fermion on the surface of a magnetically doped topological insulator.

From Nature • Mar. 18, 2018

What that means is that all the properties of a Majorana fermion, the charge, energy, what have you, it's all zero.

From Slate • May 19, 2013