Tongue-twisting P45

Long words are common in pharmacy and medical science, but the honour of being the longest word in the Oxford English Dictionary belongs to a lung disease caused by the inhalation of fine sand and ash dust found around volcanoes. It is 45 letters long and begins with “p”, which is why word buffs refer to it as P45.

Do not reach for your continuing professional development log though, because P45 is a made-up word. It was dreamt up in 1934 by Everett Smith, or “Puzzlesmith”, president of the American National Puzzler’s League.

Mr Smith introduced the word at the league’s 103rd semi-annual meeting in New York to illustrate the increasingly tongue twisting medical terminology of the time. The word was reported in the New York Herald-Tribune in February 1935, and used in a puzzle book, ‘Bedside nanna’, the following year. P45 first appeared in the 1939 supplement to the Merriam-Webster New International Dictionary and has been so often recorded since that many publishers have included it in their larger dictionaries, albeit usually with disclaimers.

If you ever have cause to discuss pneumonoultramicroscopicsilico-volcanoconiosis, you may wish to use the snappier popular terms “silicosis” or “black lung”. But if you like long words, some of the best are found in science. Although you won’t find it in a dictionary, the chemical name for the protein titin contains 189,819 let­ters.

You may also be interested to know that the longest word with its letters in alphabetical order is Aegilops, a grass genus.