thiabendazole UK /ˌθʌɪ.əˈbɛn.də.zəʊl/US /ˌθaɪ.əˈbɛn.dəˌzoʊl/ noun1 •A synthetic compound with anthelmintic properties, derived from thiazole and used chiefly to treat infestation with intestinal nematodes. formsthiabendazoles