The identity of the longest word in English depends upon the definition of what constitutes a word in the English language, as well as how length should be compared. In addition to words derived naturally from the language’s roots (without any known intentional invention), English allows new words to be formed by coinage and construction; place names may be considered words; technical terms may be arbitrarily long. Length may be understood in terms of orthography and number of written letters, or (less commonly) phonology and the number of phonemes.
|Methionylthreonylthreonylglutaminylarginyl…isoleucine||189,819||Chemical name of titin, the largest known protein||Technical; not in dictionary; disputed whether it is a word|
|Methionylglutaminylarginyltyrosylglutamyl…serine||1,909||Longest published word||Technical|
|Lopadotemachoselachogaleokranioleipsano…pterygon||183||Longest word coined by a major author, the longest word ever to appear in literature.||Coined; not in dictionary; Ancient Greek transliteration|
|Pneumonoultramicroscopicsilicovolcanoconiosis||45||Longest word in a major dictionary||Technical; coined to be the longest word|
|Supercalifragilisticexpialidocious||34||Famous for being created for the Mary Poppins film and musical||Coined|
|Pseudopseudohypoparathyroidism||30||Longest non-coined word in a major dictionary||Technical|
|Floccinaucinihilipilification||29||Longest unchallenged nontechnical word||Coined|
|Antidisestablishmentarianism||28||Longest non-coined and nontechnical word|
|Honorificabilitudinitatibus||27||Longest word in Shakespeare’s works; longest word in the English language featuring alternating consonants and vowels.||Latin|
The longest word in any of the major English language dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis, a word that refers to a lung disease contracted from the inhalation of very fine silica particles, specifically from a volcano; medically, it is the same as silicosis. The word was deliberately coined to be the longest word in English, and has since been used 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, 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).
The longest non-technical word in major dictionaries is floccinaucinihilipilification at 29 letters. Consisting of a series of Latin words meaning “nothing” and defined as “the act of estimating something as worthless”; its usage has been recorded as far back as 1741.
Ross Eckler has noted that most of the longest English words are not likely to occur in general text, meaning non-technical present-day text seen by casual readers, in which the author did not specifically intend to use an unusually long word. According to Eckler, the longest words likely to be encountered in general text are deinstitutionalization and counterrevolutionaries, with 22 letters each.
A computer study of over a million samples of normal English prose found that the longest word one is likely to encounter on an everyday basis is uncharacteristically, at 20 letters.
The words Internationalization and localization are abbreviated “i18n” and “l10n”, respectively, the embedded number representing the number of letters between the first and the last.
Smiles, according to an old riddle, may be considered the longest word in English, as there is a mile between the first and last letter. A retort asserts that beleaguered is longer still, since it contains a league. The riddle and both jocular answers date from the 19th century.
In the old time radio retrospective, Golden Radio, comedian Jack Benny jokes that “the longest word in the English language is the one that follows, ‘Now, here’s a word from our sponsor.'”