Pneumonoultramicroscopicsilicovolcanoconiosis (listen (help·info), also spelle Pneumonoultramicroscopicsilicovolcanokoniosis) is, according to the Oxford English Dictionary, "a factitious word alleged to mean 'a lung disease caused by the inhalation of very fine silica dust causing inflammation in the lungs. Occurring chiefly as an instance of a very long word.". It was coined to serve as the longest English word and is the longest word ever to appear in an English language dictionary. This 45-letter word, referred to as P45, first appeared in the 1939 supplement to the Merriam-Webster New International Dictionary, Second Edition. It is listed in the current edition of several dictionaries. A condition meeting the word's definition is normally called silicosis.