An Etymological Dictionary of the German Language/Annotated/Strahl
Strahl, masculine, ‘ray, beam,’ from Middle High German strâl, strâle, masculine and feminine, Old High German strâla, feminine, ‘arrow, flash of lightning’ (Old High German donerstrâla, ‘flash of lighting’); corresponding to Dutch straal, Anglo-Saxon strœ̂l, ‘arrow.’ These West Teutonic cognates (whence Italian strale, ‘arrow’) are closely connected with Old Slovenian strěla, ‘arrow’ (whence Russian strěla, ‘arrow,’ hence Strelitze literally ‘marksman, archer’). To these are allied strahlen, ‘to beam, radiate’ (occurring in ModHG only), and also the following word.