An Etymological Dictionary of the German Language/Annotated/nagen

by Friedrich Kluge

nagen, verb, ‘to gnaw, nibble,’ from the equivalent Middle High German nagen, Old High German nagan, with the earlier variant gnagan; compare Old Saxon and Anglo-Saxon gnagan, English to gnaw, Old Icelandic gnaga, ‘to gnaw.’ There are also forms with initial k instead of g, Dutch knagen, Old Low German cnagan, likewise High German chnagan, ‘to gnaw’; the form nagen originated in gnagen. To the Teutonic root gnag, knag, no correspondences have been found as yet in the non-Teutonic languages.