https://doi.org/10.1351/goldbook.K03386
Compounds in which a carbonyl group is bonded to two carbon atoms $\ce{R2C=O}$ (neither $\ce{R}$ may be $\ce{H}$).
Note: Compounds of structure such as $\ce{R3SiC(=O)R}$ are not ketones but acyl derivatives of substituted silanes.