An Etymological Dictionary of the German Language/Annotated/Grund
Grund, masculine, ‘ground, earth, basis, rudiment, reason,’ from the equivalent Middle High German grunt(d), Old High German grunt, masculine; corresponding to Dutch grond, Anglo-Saxon grund, English ground, Old Icelandic grund, ‘meadow land,’ grunnr (from grun-þus), ‘bottom of the sea;’ Gothic grundu-waddjus, ‘foundation wall.’ Gothic grundu, from pre-Teutonic ghrentu- (with t on account of Old Icelandic grunnr), cannot have originated in the Teutonic root grind (pre-Teutonic ghrendh) mentioned under Grand. No cognates are found in the non-Teutonic languages.