An Etymological Dictionary of the German Language/Strahl
Strahl, m., ‘ray, beam,’ from MidHG. strâl, strâle, m. and f., OHG. strâla, f., ‘arrow, flash of lightning’ (OHG. donerstrâla, ‘flash of lighting’); corresponding to Du. straal, AS. strœ̂l, ‘arrow.’ These West Teut. cognates (whence Ital. strale, ‘arrow’) are closely connected with OSlov. strěla, ‘arrow’ (whence Russ. strěla, ‘arrow,’ hence Strelitze lit. ‘marksman, archer’). To these are allied strahlen, ‘to beam, radiate’ (occurring in ModHG only), and also the following word.