reticuloendotheliosis Syllabification: (re·tic·u·lo·en·do·the·li·o·sis)Pronunciation: /riˌtikyəˌlōˌendōˌTHēlēˈōsəs/Definition of reticuloendotheliosis noun Medicine overgrowth of some part of the reticuloendothelial system, causing isolated swelling of the bone marrow and in severe cases the destruction of the bones of the skull. reticuloendotheliosis in other Oxford dictionaries Definition of reticuloendotheliosis in the British & World English dictionary