ketosisPronunciation: /kɪˈtəʊsɪs/Definition of ketosis noun [mass noun] Medicine a condition characterized by raised levels of ketone bodies in the body, associated with abnormal fat metabolism and diabetes mellitus. Derivatives ketoticPronunciation: /-ˈtɒtɪk/ adjective ketosis in other Oxford dictionaries Definition of ketosis in the US English dictionary