Term: down quark: a stable quark with an electric charge of -1/3 and a mass 607 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: water starwort: any of several aquatic plants having a star-shaped rosette of floating leaves; America, Europe and Asia