The identity of the longest word in English depends on the definition of " word " and of length. Words may be derived naturally from the language's roots or formed by coinage and construction. Additionally, comparisons are complicated because place names may be considered words, technical terms may be arbitrarily long, and the addition of suffixes and prefixes may extend the length of words to create grammatically correct but unused or novel words.
Different dictionaries include and omit different words. The length of a word may also be understood in multiple ways. Most commonly, length is based on orthography conventional spelling rules and counting the number of written letters.
Alternate, but less common, approaches include phonology the spoken language and the number of phonemes sounds. The longest word in any of the major English language dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis 45 letters , a word that refers to a lung disease contracted from the inhalation of very fine silica particles, [ 12 ] specifically from a volcano; medically, it is the same as silicosis.
The word was deliberately coined to be the longest word in English, [ 6 ] and has since been used [ citation needed ] in a close approximation of its originally intended meaning, lending at least some degree of validity to its claim.
The Oxford English Dictionary contains pseudopseudohypoparathyroidism 30 letters. Merriam-Webster's Collegiate Dictionary does not contain antidisestablishmentarianism 28 letters , as the editors found no widespread, sustained usage of the word in its original meaning. The longest word in that dictionary is electroencephalographically 27 letters.
