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Pneumonoultramicroscopicsilicovolcanoconiosis is, according to Oxford Dictionaries, “a long word said to mean a lung disease caused by inhaling very fine ash and sand dust.”[1] According to's 21st Century Lexicon, it is “supposedly the longest word in a dictionary.”[2]


This word was invented in 1935 by Everett M. Smith, president of the National Puzzlers' League, at its annual meeting. The word figured in the headline for an article published by the New York Herald Tribune on February 23, 1935, titled "Puzzlers Open 103d 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 name 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 members of the NPL campaigned to have it included in major dictionaries.[3]

This 45-letter word, referred to as P45,[4] first appeared in the 1939 supplement to the Merriam-Webster New International Dictionary, Second Edition.[5]

In Popular Culture[edit]

The word is the first line used in the English Rapper, Professor Green's song D.P.M.O from his 2011 album, At Your Inconvenience.

See also[edit]


  1. ^ "Definition of pneumonoultramicroscopicsilicovolcanoconiosis in Oxford dictionary (British and World English)". Oxford Dictionaries. Oxford University Press. Archived from the original on 2012-07-19. 
  2. ^ "Pneumonoultramicroscopicsilicovolcanoconiosis". Archived from the original on 2014-02-10. 
  3. ^ Cole, Chris (1999). Wordplay, A Curious Dictionary of Language Oddities. Sterling Publishing Co., Inc. pp. 106–107. ISBN 0-8069-1797-0. 
  4. ^ Cole, Chris. (1989.) "The Biggest Hoax". Word Ways: The Journal of Recreational Linguistics, via Retrieved on 2007-10-08.
  5. ^ Miller, Jeff. "A collection of word oddities and trivia: page 11, long words". (Personal website.) Retrieved on 2007-10-08.