sulfadiazine Syllabification: (sul·fa·di·a·zine)Pronunciation: /ˌsəlfəˈdīəˌzēn/ (chiefly British also sulphadiazine)Definition of sulfadiazine noun Medicine a sulfonamide antibiotic used to treat meningococcal meningitis. sulfadiazine in other Oxford dictionaries Definition of sulfadiazine in the British & World English dictionary