Compounds containing the carbonyl group, C=O. The term is commonly used in the restricted sense of aldehydes and ketones, although it actually includes carboxylic acids and derivatives.
Metal carbonyls, in which carbon monoxide is a formal ligand.
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on
structure (IUPAC Recommendations 1995))
on page 1325