/ Dictionary / Index C carbonium ion: Meaning and Definition of Find definitions for: car•bo'ni•um i"on Pronunciation: (kär-bō'nē-um), [key] an organic ion containing a positively charged carbon atom (opposed to carbanion). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Carboniferous carbonization Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language