Compound (linguistics)
Agglutinative languages tend to create very long words with derivational morphemes. Compounds may or may not require the use of derivational morphemes also.
The longest compounds in the world may be found in the Finnic and Germanic languages. In German, extremely 
extendable compound words can be found in the language of chemical compounds, where, in the cases of biochemistry and polymers, they can be practically unlimited in length, mostly because the German rule suggests combining all noun adjuncts with the noun as the very last stem. German examples include (color television set), (radio remote control), and the often quoted jocular word (originally only two Fs, Danube steamboat shipping company captain['s] hat), which can of course be made even longer and even more absurd, e.g. "Donaudampfschifffahrtsgesellschaftskapitänsmützenreinigungsausschreibungsverordnungsdiskussionsanfang" ("beginning of the discussion of a regulation on tendering of Danube steamboat shipping company captain hats") etc. According to several editions of the Guinness Book of World Records, the longest published German has 79 letters and is " Donaudampfschiffahrtselektrizitätenhauptbetriebswerkbauunterbeamtengesellschaft "("Association for Subordinate Officials of the Main Electric[ity] Maintenance Building of the Danube Steam Shipping"), but there is no evidence that this association ever actually existed. The word is so absurd that it was obviously invented as a joke, which is emphasized by the illogical use of the plural of "electricity".
Deutsches Wörterbuch
The Deutsches Wörterbuch (, "The German Dictionary"), abbreviated DWB, is the largest and most comprehensive dictionary of the German language in existence. Encompassing modern High German vocabulary in use since 1450, it also includes loanwords adopted from other languages into German. Entries cover the etymology, meanings, attested forms, synonyms, usage peculiarities, and regional differences of words found throughout the German speaking world. The dictionary's historical linguistics approach, illuminated by examples from primary source documents, makes it to German what the "Oxford English Dictionary" is to English. The first completed DWB lists over 330,000 headwords in 67,000 print columns spanning 32 volumes.