Duden

The Duden (German pronunciation: [ˈduːdn̩]) is a dictionary of the German language, first published by Konrad Duden in 1880, and later by Bibliographisches Institut GmbH. The Duden is updated regularly with new editions appearing every four or five years. As of December 2020, it is in its 28th edition. It is printed as twelve volumes, with each volume covering different aspects of the German language such as loanwords, etymology, pronunciation, synonyms, etc. The first of these volumes, Die deutsche Rechtschreibung (English: German orthography), has long been the prescriptive source for German language spelling. The Duden has become the preeminent language resource of the German language, stating the definitive set of rules regarding grammar, spelling and use of German language.