tropolonePronunciation: /ˈtrɒpələʊn/Definition of tropolone noun [mass noun] Chemistry an organic compound present in various plants, with a molecule based on a seven-membered carbon ring. Chemical formula: C7H6O2 Origin: 1940s: from tropilidine (a liquid hydrocarbon) + -ol + -onetropolone in other Oxford dictionaries Definition of tropolone in the US English dictionary