An Etymological Dictionary of the German Language/Drude
Drude, f., ‘sorceress,’ LG.; MidHG. trute, f.. ‘demoness, nightmare’; Drudenfuß, MidHG. trutenvuoȥ. In spite of its wide diffusion (Dan. drude, Gothland. druda), the form of the word is obscure, for it is impossible to see to what the MidHG. initial t and ModHG. d are related. Perhaps MidHG. trute is to be connected with the adj. traut; in that case Drude would be a euphemism similar perhaps to Gr. Eumenides.