An Etymological Dictionary of the German Language/Kern
Kern, m., ‘kerne, stone (of fruit), pith,’ from the equiv. MidHG. kërn, kërne, m. OHG. kërno, m.; corresponding to OIc. kjarne, m., ‘kernel.’ A corresponding Goth. *kaîrnó, m., is wanting (for which we have kaúrnô, n.?). AS. cyrnel, and the equiv. E. kernel are connected phonetically more nearly with Korn, since a derivative of Kern in E. would have an initial ch. OTeut. kerna- and korna- are allied by gradation to each other just as Brett and Bord, Kerl and Karl.