/ Dictionary / Index C carbonyl group: Meaning and Definition of Find definitions for: car'bonyl group" Pronunciation: [key] the bivalent radical CO, occurring in acids, ketones, aldehydes, and their derivatives. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. carbonyl chloride carbonylic Related Content Daily Word Quiz: penurious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language