lepton

¹ American  

[lep-ton] / ˈlɛp tɒn /

noun

lepta plural

1. an aluminum coin of modern Greece until the euro was adopted, one 100th of a drachma.

2. a small copper or bronze coin of ancient Greece.

---

lepton ² American  

[lep-ton] / ˈlɛp tɒn /

noun

Physics.

1. any of a class of particles with spin of ½ that are not subject to the strong force and that are believed to be truly elementary and not composed of quarks or other subunits. The leptons known or believed to exist are the electron and electron-neutrino, the muon and mu-neutrino, and the tau lepton and tau-neutrino.

---

lepton ¹ British  

/ ˈlɛptɒn /

noun

1. a former Greek monetary unit worth one hundredth of a drachma

2. a small coin of ancient Greece

---

lepton ² British  

/ ˈlɛptɒn /

noun

1. physics any of a group of elementary particles and their antiparticles, such as an electron, muon, or neutrino, that participate in electromagnetic and weak interactions and have a half-integral spin

---

lepton Scientific  

/ lĕp′tŏn′ /

1. Any of a family of elementary particles that interact through the weak force and do not participate in the strong force. Leptons include electrons, muons, tau particles, and their respective neutrinos, the electron neutrino, the muon neutrino, and the tau neutrino. The antiparticles of these six particles are also leptons.

2. Compare hadron See Note at elementary particle See Table at subatomic particle

---

lepton Cultural  

1. Any one of six elementary particles that are one of the fundamental constituents of matter. Leptons are not affected by the strong force and are not normally found in the nucleus of the atom. The electron and the neutrino are examples of leptons.

---

Other Word Forms

Derived Forms

• leptonic
  adjective

Inflected Forms

Nouns

• lepta
  plural

Etymology

Origin of lepton¹

First recorded in 1715–25; from Greek leptón (nómisma) “a small (coin),” noun use of neuter of leptós small; see lepto-

Origin of lepton²

1948; < Greek, neuter of leptós small, slight; see lepto-, -on ¹

Example Sentences

See Examples For:

lepton lepta

Observing such a process would break a fundamental rule of particle physics called lepton flavor conservation, which is a key part of the Standard Model, and would provide direct evidence for physics beyond existing theories.

From Science Daily ● Feb. 2, 2026

To achieve this, the team refined RHIC's detectors to isolate low-momentum lepton pairs and reduce background noise.

From Science Daily ● Oct. 29, 2025

During this process the beauty quark turns into a strange quark and produces a pair of leptons—specifically, a lepton and its antimatter partner.

From Scientific American ● Nov. 14, 2022

On the surface, this quantity is not related to lepton flavor universality, and I didn’t find the measurement very exciting at first.

From Scientific American ● Nov. 14, 2022

A lepton is a very small brass Jewish coin worth half a Roman quadrans each, which is worth a quarter of the copper assarion.

From The World English Bible (WEB): Luke by Anonymous

One of the women of the cabin I had visited followed me to the museum, and naturally held out her hand for "pende lepta."

From From the Oak to the Olive A Plain record of a Pleasant Journey by Howe, Julia Ward

A kodrantes is a small coin worth one half of an Attic chalcus or two lepta.

From The World English Bible (WEB): by Anonymous

Before the letters came, last evening, we heard continual cries of "Pende lepta," betokening the issue of an extra.

From From the Oak to the Olive A Plain record of a Pleasant Journey by Howe, Julia Ward

There are nickel coins of 20, 10 and 5 lepta, copper coins of 10 and 5 lepta.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 4 "Grasshopper" to "Greek Language" by Various

The monetary unit is the new drachma, equivalent to the franc, and divided into 440 100 lepta or centimes.

From Encyclopaedia Britannica, 11th Edition, Volume 12, Slice 4 "Grasshopper" to "Greek Language" by Various