Longest word in English
The identity of the longest word in English depends on the definition of a 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).
| Word | Letters | Meaning | Claim | Dispute |
|---|---|---|---|---|
| methionylthreonylthreonylglutaminylalanyl...isoleucine | 189,819 | The chemical composition of titin, the largest known protein | Longest known word overall by magnitudes. Attempts to say the entire word have taken two to three and a half hours. | Technical; not in dictionary; whether this should actually be considered a word is disputed |
| methionylglutaminylarginyltyrosylglutamyl...serine | 1,909 | The chemical name of E. coli TrpA (P0A877) | Longest published word | Technical |
| lopadotemachoselachogaleokranioleipsano...pterygon | 183 | A fictional dish of food | Longest word coined by a major author, the longest word ever to appear in literature | Contrived nonce word; not in dictionary; Ancient Greek transliteration |
| pneumonoultramicroscopicsilicovolcanoconiosis | 45 | The disease silicosis | Longest word in a major dictionary | Contrived coinage to make it the longest word; technical, but only mentioned and never actually used in communication |
| supercalifragilisticexpialidocious | 34 | Unclear – generally understood as a positive adjective or a nonsense word | Made popular in the Mary Poppins film and musical | Contrived coinage |
| pseudopseudohypoparathyroidism | 30 | A hereditary medical disorder | Longest non-contrived word in a major dictionary | Technical |
| antidisestablishmentarianism | 28 | The political position of opposing disestablishment | Longest non-contrived and nontechnical word | Not all dictionaries accept it due to lack of usage. |
| honorificabilitudinitatibus | 27 | The state of being able to achieve honors | Longest word in Shakespeare's works; longest word in the English language featuring alternating consonants and vowels | Latin |