An Etymological Dictionary of the German Language/Annotated/Boden
Boden, masculine, ‘bottom, ground, soil, loft,’ from the equivalent Middle High German boden, bodem, genitive bodemes (the dialectic Modern High German bodem is stil used, compare the proper name Bodmer), Old High German bodam, masculine, which still exists in the cognate dialects and languages. Old High German bodam points, however, not to Gothic *buþma-, but, with a remarkable irregularity, to *budna-, the corresponding Anglo-Saxon botm, English bottom, exhibiting a further irregularity in the dental. Gothic *budna- seems probable, since the non-Teutonic languages of the Aryan stock point to bhudhmen, bhudhnó- as the stem; Greek πυθμήν, ὁ (for *φυθμήν, see bieten), ‘bottom’; Latin fundus (for *fudnus), Sanscrit budhná- (for *bhudhná-, by the same rule as in Greek). It is a primitively Aryan word, with the meaning ‘bottom, ground,’ but is not connected, however, with a strong verb in any Aryan language. — Bodensee obtained its name during the Carolovingian period (formerly Lacus Brigantînus, ‘Lake Constance’) from the imperial palace at Bodema (now Bodmann), which may be the plural of the substantive Boden.