An Etymological Dictionary of the German Language/Nabe
Nabe, f., from the equiv. MidHG. nabe, OHG. naba, f., ‘nave (of a wheel)’; corresponding to Du. naaf, aaf, nave (see Näber, Natter), AS. nafu, f., E. nave, OIc. nǫf, f., all of which have the same meaning; Goth. *naba, f., is by chance not recorded. Both the word and the idea are OAryan (primit. form nobhâ); comp. OInd. nãbhi, f., and nãbhya, n., ‘nave (of a wheel).’ Undoubtedly the cognates discussed under Nabel with the meaning ‘navel’ are primit. allied, the Ind. word nâbhi just quoted also signifying ‘navel,’ as well as Lett. naba, f., which is exactly equiv. in sound to OHG. naba. Hence Lat. umbo (for *onbo, *nobo), ‘boss (of a shield),’ may also be connected with umbilîcus, ‘navel’; comp. Gr. ὀμφαλός, ‘navel, boss (of a shield).’ With regard to the antiquity of the terms denoting parts of a waggon see Rad, Achse, Lünse, and Deichsel.