Definition from Wiktionary, the free dictionary
See also Carbonyl
carbonyl (plural carbonyls)
- (organic chemistry) In organic chemistry, a divalent functional group, (-CO-), characteristic of aldehydes, ketones, carboxylic acids, amides, carboxylic acid anhydrides, carbonyl halides, esters and others.
- (inorganic chemistry) Any compound of a metal with carbon monoxide, such as nickel carbonyl, Ni(CO)4.
Derived terms 
functional group -CO-