thiabendazolePronunciation: /ˌθʌɪəˈbɛndəzəʊl/Definition of thiabendazole noun [mass noun] Medicine a synthetic compound with anthelmintic properties, derived from thiazole and used chiefly to treat infestation with intestinal nematodes. Origin: 1960s: from elements from thiazole + benzene + imidazolethiabendazole in other Oxford dictionaries Definition of thiabendazole in the US English dictionary