histoplasmosis Syllabification: (his·to·plas·mo·sis)Pronunciation: /ˌhistōplazˈmōsis/Definition of histoplasmosis noun Medicine infection by a fungus found in the droppings of birds and bats in humid areas. It is not serious if confined to the lungs but can be fatal if spread throughout the body. The fungus is Histoplasma capsulatum histoplasmosis in other Oxford dictionaries Definition of histoplasmosis in the British & World English dictionary