ketonePronunciation: /ˈkiːtəʊn/Definition of ketone noun Chemistry an organic compound containing a carbonyl group CO bonded to two hydrocarbon groups, made by oxidizing secondary alcohols. The simplest such compound is acetone. Derivatives ketonicPronunciation: /kɪˈtɒnɪk/ adjective Origin: mid 19th century: from German Keton, alteration of Aketon 'acetone'ketone in other Oxford dictionaries Definition of ketone in the US English dictionary