“Antidisestablishmentarianism”. It is a political position that originated in nineteenth-century Britain, in opposition to proposals to remove the Church of England’s status as the state church of Ireland and Wales (Source: Wikipedia).
Well, it’s the longest word that is not a scientific name. The longest word in the English dictionary, as recorded by Guinness Book of World Records, is “pneumonoultramicroscopicsilicovolcanoconiosis” at 45 characters. “pneumonoultramicroscopicsilicovolcanoconiosis” is used to refer to a lung disease caused by the inhalation of very fine silica dust, causing inflammation in the lungs. Oh a medical term. And you know why doctors scribble? They couldn’t spell.