An Etymological Dictionary of the German Language/Annotated/Wahrzeichen
Wahrzeichen, neuter, ‘mark, token, omen, signal,’ from Middle High German warzeichen, neuter, ‘token, mark,’ for which the equivalent Middle High German and Old High German wortzeichen (Old Saxon wordtêkan), neuter, is ordinarily used. The word has been corrupted; its primitive form and meaning are obscure. Compare also the cognate, Old Icelandic jartein, ‘token of recognition.’