/ Dictionary / Index C carbon 13: Meaning and Definition of Find definitions for: carbon 13 Pronunciation: (kär'bun thûr-tēn'). [key] the stable isotope of carbon having an atomic mass number 13, used as a tracer. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. carbon 12 carbon 14 Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language