cyclophosphamide Syllabification: (cy·clo·phos·pha·mide)Pronunciation: /ˌsīklōˈfäsfəˌmīd/Definition of cyclophosphamide noun Medicine a synthetic cytotoxic drug used in treating leukemia and lymphoma and as an immunosuppressive agent. cyclophosphamide in other Oxford dictionaries Definition of cyclophosphamide in the British & World English dictionary