An Etymological Dictionary of the German Language/Süden
Süden, m., ‘south’; the strictly HG. form is Sund, which survives in the proper names Sundgau, Sundheim, &c.; comp. OHG. sundwint, ‘south wind,’ sundarwint (MidHG. sunderwint). Yet the simple form of the word became obsolete at an early period in UpG. (the term used being Mittag), the names of the other cardinal points being also unknown. The loss of the n in Süden (MidHG. sunden. OHG. sundan) points to the adoption of the word from LG. The primit. Teut. stem sunþ-, ‘south,’ is also assumed by OIc. sunnan, AS. sûðan, ‘from the south,’ AS. sûð, Du. zuid, OSax. sûth, ‘south.’ The term sunþ-, ‘south,’ is as specifically Teut. as Norden and Westen. Whether sunþ- is derived from sun-, in Goth. sun-nô, ‘sun,’ and means lit. ‘sun-side,’ is not certain (yet note Osten as ‘dawn-side’).