An Etymological Dictionary of the German Language/Annotated/Spur
Spur, feminine, ‘track, trace, footsteps, vestige,’ from Middle High German spur (spür), neuter and feminine, ‘footstep,’ beside which the equivalent Middle High German and Old High German spor occurs; connected with the Teutonic and Aryan root sper (see Sporn), ‘to tread.’ To this is allied the Modern High German denominative spüren, ‘to trace, investigate, discover,’ from Middle High German spürn, Old High German spuren, spurren, and spurien, weak verb, literally ‘to follow in search of the track of game,’ then ‘to go in quest of, trace, examine.’ This figurative sense recurs in all the Teutonic languages (compare Dutch speuren, Anglo-Saxon spyrian, Old Icelandic spyrja), and is probably a relic of the terms used by Old Teutonic hunters.