coumarone Syllabification: (cou·ma·rone)Pronunciation: /ˈko͞oməˌrōn/Definition of coumarone noun Chemistry an organic compound present in coal tar, used to make thermoplastic resins chiefly for paints and varnishes. A bicyclic compound with fused benzene and furan rings; chemical formula: C8H6O Origin: late 19th century: from coumarin + -onecoumarone in other Oxford dictionaries Definition of coumarone in the British & World English dictionary