radioactive series

WordReference Random House Unabridged Dictionary of American English © 2025

ra′dioac′tive se′ries, [Physics, Chem.]

1. Physics a succession of elements initiated in the radioactive decay of a parent, as thorium or uranium, each of which decays into the next until a stable element, usually lead, is produced. Also called decay series. 

• 1920–25

Collins Concise English Dictionary © HarperCollins Publishers::

radioactive series noun

1. a series of nuclides each of which undergoes radioactive decay into the next member of the series, ending with a stable element, usually lead
   See uranium series, thorium series