chlorpromazine UK /klɔːˈpɹəʊ.məz.ɪn/US /klɔɹˈpɹɑm.əˌziːn/ noun1 •A synthetic antipsychotic drug, with the chemical formula C₁₇H₁₉ClN₂S.Chlorpromazine should be taken with caution in combination with barbiturates, sleeping pills, narcotics, or any other medication which may produce a depressive effect. Avoid alcohol. — 1979 formschlorpromazines