fulminant
adjective
ful·mi·nant ˈfu̇l-mə-nənt 
ˈfəl-
: coming on suddenly and with great severity
fulminant disease
Example Sentences
Recent Examples on the Web The other possibility is a life-threatening fungal infection called acute fulminant fungal rhinosinusitis. 
Amy Marturana, SELF, 26 Dec. 2018
Amy Marturana, SELF, 26 Dec. 2018 Word History
First Known Use
1838, in the meaning defined above
Medical Definition
fulminant
adjective
ful·mi·nant ˈfu̇l-mə-nənt, ˈfəl-
: coming on suddenly with great severity
fulminant hepatitis with total hepatocyte necrosis C. L. Humberston et al.
C. L. Humberston et al.