saprolegniaPronunciation: /ˌsaprə(ʊ)ˈlɛgnɪə/Definition of saprolegnia noun [mass noun] an aquatic fungus which can attack the bodies of fish and other aquatic animals. Genus Saprolegnia, subdivision Mastigomycotina Origin:modern Latin, from sapro- 'of decay' + Greek legnon 'border'saprolegnia in other Oxford dictionaries Definition of saprolegnia in the US English dictionary