German orthography
Compound words, including nouns, are written together, e.g. "Haustür" (Haus+Tür; house door), "Tischlampe" (Tisch+Lampe; table lamp), "Kaltwasserhahn" (Kalt+Wasser+Hahn; cold water tap/faucet). This can lead to long words: the longest word in regular use, "Rechtsschutzversicherungsgesellschaften" ("legal protection insurance companies"), consists of 39 letters; while the longest German word ever published ("Donaudampfschiffahrtselektrizitätenhauptbetriebswerkbauunterbeamtengesellschaft", "Association for subordinate officials of the head office management of the Danube steamboat electrical services") has 79 letters.
Duden
The () is a dictionary of the German language, first published by Konrad Duden in 1880. The " is updated regularly with new editions appearing every four or five years. , it is in its 27th edition. It is printed as twelve volumes, with each volume covering different aspects of the German language such as loanwords, etymology, pronunciation, synonyms, etc.