lepton /ˈlɛptɒn/ noun3 •An elementary particle that has a spin of 1/2 (i.e., is a fermion) and does not interact via the strong nuclear force; examples include the electron, the muon, the neutrino and the tauon. •A coin used since ancient times in Greece, serving in modern times as one hundredth of a phoenix, a drachma, and a euro (as the Greek form of the Eurocent). •A small, bronze Judean coin from the 1st century BCE, considered by some to be the widow's mite. formslepta · leptons