The longest word in the English language according to Guinness is
FLOCCINAUCINIHILIPILIFICATION.
The lung disease one is the longest unnofficial word, cos it's a compound scientific term, and it's possible to make sceintific names stupidly long, like the 1700+ character one, but that's
neverbeen in a dictionary.
The longest word entered in a dictionary anywhere is Swedish, and it's NORDOSTERSJOKUSTARTILLERIFLYGSPANINGSSIMULATORANLAGG-
NINGSMATERIELUNDERHALLSUPPFOLJNINGSSYSTEMDISKUSSIONS-
INLAGGSFORBEREDELSEARBETEN, which means "preparatory work on the contribution to the discussion on the maintaining system of support of the material of the aviation survey simulator device within the north-east part of the coast artillery of the Baltic."
Other
fun long words - DONAUDAMPFSCHIFFAHRTSELEKTRIZITAETENHAUPTBETRIEBSWERKBAUUNTERBEAMTENGESELLSCHAFT
DIKETIDAKNYAHCASDIVERSIFIKASIELEKTROSTATIKKAN
KINDERCARNIVALSOPTOCHTVOORBEREIDINGSWERKZAAMHEDEN