An Etymological Dictionary of the German Language/Annotated/Ecker
Ecker, feminine, ‘acorn,’ simply Modern High German, from Middle German and Low German ecker, ‘acorn, beech nut’; there is also in Upper German a word *acheren primitively allied and equivalent to Swiss ackeram (Bavarian akram). Compare the corresponding Gothic akran, neuter, ‘produce, fruit (generally),’ Old Icelandic akarn, neuter, Anglo-Saxon œcern, English acorn, Dutch aker, ‘acorn.’ Since the meaning ‘acorn, beechnut,’ is a recent specialisation in comparison with Gothic akran, ‘produce, fruit,’ the cognates nay be connected with Gothic akrs, High German Acker, and perhaps also with Lithuanian ŭga, ‘berry,’ unless the later is more closely allied to Latin uva. In any case its kinship with Eiche must be denied, since the latter would be *aiks in Gothic. The mutation of the stem in Modern High German and Low German Ecker must be explained by a Gothic *akrin.