/ Dictionary / Index U uranium series: Meaning and Definition of Find definitions for: ura'nium se"ries Pronunciation: (yoo-rā'nē-um-rā'dē-um). [key] — Chem. Chem. the radioactive series that starts with uranium 238 and ends with a stable isotope of lead of mass number 206. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. uranium oxide urano- Related Content Daily Word Quiz: blanch Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language