It has been said by many that 'Supercalifragilisticexpiallydocious', in fact, the longest word in the English language. It's ridiculously long, I'll grant you that, but many are of the opinion that they just don't care if it is in the Oxford English Dictionary. Some even go so far as to state that it is no more than a long piece of complete and utter gibberish.
There is, for example, 'Pneumonoultramicroscopicsilicovolcanoconiosis' (which the very same Oxford English Dictionary defines as "a factitious word alleged to mean 'a lung disease caused by the inhalation of very fine silica dust' but occurring chiefly as an instance of a very long word").
'Llanfairpwllgwyngyllgogerychwyrndrobwllllantysiliogogogoch' is the name of a small village in Wales, which is a very long name for a place, but there are longer place names on this planet. For one, there's 'Taumatawhakatangihangakoauauotamateaturipukakapikimaungahoronukupokaiwhenuakitanatahu', a thousand-foot-high mountain in New Zealand, which means that it's still smaller than its name. Meaning "the place where Tamatea, the man with the big knees, who slid, climbed and swallowed mountains, known as land-eater, played his flute to his loved one", it is the longest place name recognised by the Oxford English Dictionary.
The Thai city of Bangkok's full name is 'Krungthep Mahanakhon Bovorn Ratanakosin Mahintharayutthaya Mahadilokpop Noparatratchathani Burirom Udomratchanivet Mahasathan Amornpiman Avatarnsathit Sakkathattiyavisnukarmprasit', although this has not yet been recognised by the Guinness Book of Records.
'Floccinaucinihilipilification' is also rather long. In fact, it's the longest technical world in the Oxford English Dictionary. Yet in spite all of this, it is not uncommon for humans to go to great lengths to create a word longer than the current longest word. It's just what they do.
This word is a Tryptophan synthetase A protein, an enzyme that has 267 amino acids, and makes a record of 1,909 letters. It is the term for the formula C1289H2051N343O375S8. Because this is a chemical formula, it may not actually be considered a word as such. It is actually quite likely that the formula is deliberately so long because whoever discovered or named it either wanted to annoy people like me compiling lists or writing these sort of entries or just wanted to get into the Guinness Book of Records.
Shortly after this word was invented, it has been rumoured that the typists, editors and printers for the Shorter Oxford English Dictionary went on strike for having to type out, print and edit something that flipping long. In the end, it wasn't added to the dictionary.
In fact, the editors of this Guide may have problems editing it as well.
Please note that, as some have pointed out, there really can be no fixed longest word in English, like most languages, is one that is in a continual state of evolution and Man will just continually create longer and longer words that will evolve themselves into ridiculously long travesties of the English language.