cyclophosphamidePronunciation: /ˌsʌɪklə(ʊ)ˈfɒsfəmʌɪd/Definition of cyclophosphamide noun [mass noun] Medicine a synthetic cytotoxic drug used in treating leukaemia and lymphoma and as an immunosuppressive agent. cyclophosphamide in other Oxford dictionaries Definition of cyclophosphamide in the US English dictionary