An Etymological Dictionary of the German Language/Annotated/schnurren
schnurren, verb, ‘to hum, whiz, buzz, purr,’ from Middle High German snurren, ‘to rustle, drink (of beasts).’ Allied to Modern High German Schnurre, feminine, ‘humming-top, farce,’ and the derivative schnurrig, ‘droll’; compare Old High German snurring, Middle High German snürrinc (also snurrœre), 'buffoon, fool'; perhaps Narr, ‘fool,’ Old High German narro, is a cognate term. —