An Etymological Dictionary of the German Language/Annotated/Krieg
Krieg, masculine, ‘war,’ from Middle High German kriec(g), masculine, ‘exertion, endeavour to obtain something,’ then also ‘opposition, resistance, argument, discord, combat.’ The predominant meaning in Modern High German is the latest and ‘counter-effort' the earliest; compare Middle High German einkriege, adjective, ‘self-willed.’ For a similar evolution of meaning compare Old High German flîȥ, ‘exertion, zeal, quarrel'; see Fleiß. The word is almost entirely unknown to Old High German; it occurs once as chrêg, ‘pertinacia,’ with which widarkrêgi, ‘controversia', widarkriegelîn, ‘obstinatus’ (with obscure ê, ia, ie), are connected. This word, obscure in origin, is shared only by Dutch (krijg) with German; in all the other Teutonic languages it is wanting, Danish and Swedish krig being borrowed from German. Compare the following word.