radioactive series
Physics
noun
A series of radioactive nuclides each member of which decays into the next, together with a non-radioactive end product; the series of transformations relating such a set of nuclides; especially each of four such series occurring among the nuclides heavier than lead (the thorium, actinium, and radium (or uranium) series, which occur naturally and terminate with different isotopes of lead, and the neptunium series).
Origin
Early 20th century; earliest use found in Journal of the American Chemical Society.