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".
Till Backhaus
The is defined using a grammatically valid and usable compound noun of 63 letters. The word featured in the "Guinness Book of Records" until 1996 when it was controversially challenged for the top spot by the creation of a longer word. But for many the word created by Backhaus's ministry was toppled from its position as Germany's longest official word only in 2013 when it was withdrawn from use by the regional assembly because the law it defined had been repealed.