An Etymological Dictionary of the German Language/Narr
Narr, m., ‘fool,’ from MidHG. and MidLG. narre, m., ‘simpleton, fool,’ OHG. narro, m. ‘madman’; a word peculiar to G., the origin of which is totally obscure. The derivation from MidLat. nârio, ‘sneerer, scoffer, subsannans,’ is not satisfactory, since the Lat. word would be represented by a different form in G.; moreover, there is no reason, as far as the meaning is concerned, to suppose that the word was borrowed (see Gaukler). Allied to OHG. snurring, MidHG. snürrine, ‘buffoon, fool’?.