"At 45 letters, it is certainly the longest word ever to appear in a non-technical dictionary of English, the Oxford English Dictionary. However there are strong indications that the word was coined by puzzler Everett Smith in 1935 as a hypothetical long word that could result from the protraction of medical terms. The actual name of the disease is pneumoconiosis, which is 14 letters long."
http://en.wikipedia.org/wiki/Longest_word_in_English#Popular_usage
Floccinaucinihilipilification is the longest "official" word in the English language, even longer than Antidisestablishmentarianism, but is longer really better and is English really best?