As a technical term, the "high" in High German is a geographical reference to the group of dialects that forms "High German" (i.e. "Highland" German), out of which developed Standard German, Yiddish and Luxembourgish. It refers to the Central Uplands (Mittelgebirge) and Alpine areas of central and southern Germany; it also includes Luxembourg, Austria, Liechtenstein, and most of Switzerland. This is opposed to Low German, which is spoken in the lowlands and along the flat sea coasts of the North German Plain.1
High German can be subdivided into Upper German (Oberdeutsch) and Central or Middle German (Mitteldeutsch, this includes Luxembourgish, which itself is now a standard language).2
High German varieties are distinguished from other West Germanic varieties in that they took part in the High German consonant shift (c. AD 500) to various degrees. To see this, compare the following:3
In the southernmost High Alemannic dialects, there is a further shift: Sack (like English/Low German "sack/Sack") is pronounced [z̥ak͡x] ([k] to [k͡x]).
See also: Theodiscus
Old High German evolved from about 500 AD. Around 1200 the Swabian and East Franconian varieties of Middle High German became dominant as a court and poetry language (Minnesang) under the rule of the House of Hohenstaufen.
The term "High German" as spoken in central and southern Germany (Upper Saxony, Franconia, Swabia, Bavaria) and Austria was first documented in the 15th century.4
Gradually driving back Low German variants since the Early modern period, the Early New High German varieties, especially the East Central German of the Luther Bible, formed an important basis for the development of Standard German.5
Divisions between subfamilies within Germanic are rarely precisely defined, because most form continuous clines, with adjacent dialects being mutually intelligible and more separated ones not. In particular, there has never been an original "Proto-High German". For this and other reasons, the idea of representing the relationships between West Germanic language forms in a tree diagram at all is controversial among linguists. What follows should be used with care in the light of this caveat.
Compare the definition of "high" in the Oxford English Dictionary (Concise Edition): "... situated far above ground, sealevel, etc; upper, inland, as ... High German". ↩
E.g. Hermann Niebaum, Jürgen Macha, Einführung in die Dialektologie des Deutschen (series: Germanistische Arbeitshefte), 2nd ed., Max Niemeyer Verlag, Tübingen, 2006, p. 220 [1st ed. 1999, 3rd ed. 2014] Gabriele Graefen, Martina Liedke-Göbel, Germanistische Sprachwissenschaft: Deutsch als Erst-, Zweit- oder Fremdsprache, 3rd ed., 2020, p. 31. For the Middle High German time e.g.: Howard Jones & Martin H. Jones, The Oxford Guide to Middle High German, Oxford University Press, 2019, p. 7 M. O'C. Walshe, A Middle High German reader with grammar, notes, and glossary, Oxford University Press, 1974, p. 3 ↩
Robinson, Orrin. Old English and its Closest Relatives. Routledge, 1994. /wiki/Orrin_W._Robinson_(philologist) ↩
"Understanding High German: The Standardized Linguistic Bridge of the German-Speaking World". www.verbalplanet.com. Retrieved 2025-03-12. https://www.verbalplanet.com/learn-german/blog/what-is-high-german-language.asp ↩
Russ, Charles V.J. The German Language Today: A Linguistic Introduction. Routledge, 1994, p. 15f. ↩