An Etymological Dictionary of the German Language/Annotated/ärgern

ärgern, ‘to annoy, vex, fret,’ from Middle High German ergern, ‘to incite to evil, deteriorate, corrupt,’ Old High German ergirôn, argirôn, ‘to make worse,’ from the comparative of arg. From this Modern High German Ärger, masculine, is formed (compare Aussatz from aussätzig, Geiz from geizen, Handel from handeln, Opfer from opfern); in Middle High German erge, Old High German argî, feminine, ‘malice.’ — ärgern, verb, see arg.