Pronunciation: (lep'ton),[key] —n., —pl.-taPronunciation: (-tu).[key] 1. an aluminum coin of modern Greece, the 100th part of a drachma.
2. a small copper or bronze coin of ancient Greece.
Pronunciation: (lep'ton),[key] —n.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. Cf. conservation of lepton number.