/ Dictionary / Index R radiocarbon: Meaning and Definition of Find definitions for: ra•di•o•car•bon Pronunciation: (rā"dē-ō-kär'bun), [key] — n. Chem. Also calleda radioactive isotope of carbon with mass number 14 and a half-life of about 5730 years: widely used in the dating of organic materials. any radioactive isotope of carbon. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: radiocarbon (Thesaurus) radio car radiocarbon dating Related Content Daily Word Quiz: modify Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language