Term: top quark: a hypothetical quark with a charge of +2/3 and a mass more than 100,000 times that of an electron
Broader: quark: (physics) hypothetical truly fundamental particle in mesons and baryons; there are supposed to be six flavors of quarks (and their antiquarks), which come in pairs; each has an electric charge of +2/3 or -1/3 | Unrelated: genus sassafras: a genus of sassafras