1 [lep-ton]
noun, plural lepta [lep-tuh] .
an aluminum coin of modern Greece until the euro was adopted, the 100th part of a drachma.
a small copper or bronze coin of ancient Greece.

1715–25; < Greek leptón (nómisma) a small (coin), noun use of neuter of leptós small; see lepto-

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2 [lep-ton] .
noun Physics.
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.

1948; < Greek, neuter of leptós small, slight; see lepto-, -on1

leptonic, adjective
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World English Dictionary
lepton1 (ˈlɛptɒn)
n , pl -ta
1.  a former Greek monetary unit worth one hundredth of a drachma
2.  a small coin of ancient Greece
[from Greek lepton (nomisma) small (coin)]

lepton2 (ˈlɛptɒn)
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
[C20: from lepto- + -on]

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Word Origin & History

1948, from Gk. leptos "small, slight, slender, delicate" + -on.
Online Etymology Dictionary, © 2010 Douglas Harper
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American Heritage
Medical Dictionary

lepton lep·ton (lěp'tŏn')
Any of a family of elementary particles that participate in the weak interaction, including the electron and its associated neutrino.

The American Heritage® Stedman's Medical Dictionary
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American Heritage
Science Dictionary
lepton   (lěp'tŏn')  Pronunciation Key 
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. Compare hadron. See Note at elementary particle. See Table at subatomic particle.
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American Heritage
Cultural Dictionary
lepton [(lep-ton)]

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.

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Example sentences
The others are more unstable than any respectable quark, boson or lepton.
Injecting nucleon decay electrons and positrons into a rotating dark energy star will result in a highly collimated lepton jet.
It includes lepton and hadron colliders presently in operation, under construction or under development.
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