a former monetary unit of modern Greece, equal to of a drachma
Origin:
Gr < leptos, thin, small < lepein, to peel: see leper
noun
Particle Physics any of a class of fermions subject to the weak interaction but not the strong interaction, as the electron, neutrino, muon, or tau particle
Any of a family of elementary particles that participate in the weak interaction, including the electron, the muon, and their associated neutrinos. See Table at subatomic particle.