sulphadiazinePronunciation: /ˌsʌlfəˈdʌɪəziːn/ (US sulfadiazine)Definition of sulphadiazine noun [mass noun] Medicine a sulphonamide antibiotic used to treat meningococcal meningitis. sulphadiazine in other Oxford dictionaries Definition of sulphadiazine in the US English dictionary