An Etymological Dictionary of the German Language/Annotated/drohen
drohen, verb, ‘threaten,’ from the equivalent Middle High German drôu, weak verb, which is the denominative of an earlier dro, feminine, ‘threat.’ The more ancient verb is Modern High German dräuen, from Middle High German dröuwen, drouwen, Old High German dręwen, drouwen; Gothic *þraujan, Anglo-Saxon þreán þreáde) (equivalent to English to threaten). Old High German drô, drôa (genitive drawa), corresponds to Anglo-Saxon þreá; Gothic þrawa is wanting, genitive þrawôs, feminine, ‘threat.’ In English the word is obsolete. Beyond Teutonic there are no cognates.