The Collaborative International Dictionary of English v.0.48:
Fulminant \Ful"mi*nant\, a. [L. fulminans, p. pr. of fulminare to lighten: cf. F. fulminant.] Thundering; fulminating. [R.] --Bailey. [1913 Webster]WordNet (r) 3.0 (2006):
fulminant adj 1: sudden and severe; "fulminant pain"; "fulminant fever"