Pneumonoultramicroscopicsilicovolcanoconiosis (/ˌnjmənˌʌltrəˌmkrəˈskɒpɪkˌsɪlɪkvɒlˌknˌkniˈsɪs/ (audio speaker iconlisten)[1][2]) is a word coined by the president of the National Puzzlers' League as a synonym for the disease known as silicosis. It is the longest word in the English language published in a dictionary, Oxford Dictionaries, which defines it as "an artificial long word said to mean a lung disease caused by inhaling very fine ash and sand dust".[3]

Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. It is a type of pneumoconiosis.


The word can be analysed like this:

  1. Pneumono: from ancient Greek (pneúmōn) which means lungs
  2. ultra: beyond
  3. microscopic: referring to the fineness of particulates
  4. silico-: silicon, referring to silicate dust
  5. volcano: referring to volcanic dust
  6. coni: from ancient Greek (kónis) which means dust
  7. -osis: suffix to indicate a medical condition

This word was invented in the annual meeting of the National Puzzlers' League (N.P.L.) by its president Everett M. Smith. The word featured in the headline for an article published by the New York Herald Tribune on February 23, 1935, titled "Puzzlers Open 103rd Session Here by Recognizing 45-Letter Word":

Pneumono­ultra­microscopic­silico­volcano­coniosis succeeded electrophotomicrographically as the longest word in the English language recognized by the National Puzzlers' League at the opening session of the organization's 103rd semi-annual meeting held yesterday at the Hotel New Yorker. The puzzlers explained that the forty-five-letter word is the synonym of a special form of pneumoconiosis caused by ultra-microscopic particles of silica volcanic dust...

Subsequently, the word was used in a puzzle book, Bedside Manna, after which time, members of the N.P.L. campaigned to include the word in major dictionaries.[4]

This 45-letter word, referred to as "P45",[5] first appeared in the 1939 supplement to the Merriam-Webster New International Dictionary, Second Edition.[6]

See alsoEdit


  1. ^ "Pneumonoultramicroscopicsilicovolcanoconiosis". Oxford Dictionaries UK English Dictionary. Oxford University Press. n.d. Retrieved 2017-10-10.
  2. ^ "Pneumonoultramicroscopicsilicovolcanoconiosis". Merriam-Webster Dictionary.
  3. ^ "Definition of pneumono­ultra­microscopic­silico­volcano­coniosis in Oxford dictionary (British and World English)". Oxford Dictionaries. Oxford University Press. Archived from the original on 2012-07-19.
  4. ^ Cole, Chris (1999). Wordplay, A Curious Dictionary of Language Oddities. Sterling Publishing Co., Inc. pp. 106–107. ISBN 0-8069-1797-0.
  5. ^ Cole, Chris. (1989.) "The Biggest Hoax" Archived 2014-08-10 at the Wayback Machine. Word Ways: The Journal of Recreational Linguistics, via Retrieved on 2007-10-08.
  6. ^ Miller, Jeff. "A collection of word oddities and trivia: page 11, long words". (Personal website.) Retrieved on 2007-10-08.

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