A inflammation of the lungs due to chronic inhalation of irritant mineral particles. Also known as
black lung and
silicosis.
The more interesting version of this term is pneumonoultramicroscopicsilicovolcanoconiosis, a 45-letter word alleged to be the longest in the English language. It supposedly means "inflammation of the lungs due to chronic inhalation of microscopic volcanic silica."
The first recorded appearance of the word occured when the New York-based National Puzzlers League recognized the it as the longest word at its 103rd session in 1935. The word has not been found in any prior publication and was apparently fabricated by Everett M. Smith, president of the NPL and the news editor of the Christian Science Monitor.
On the authority of the National Puzzlers League's pronouncement the word briefly made it into Mirriam Webster's Unabridged Dictionary, but was later removed.
The OED does not give the word its own entry, but gives this definition under "pneumono-":
pneumonoultramicroscopicsilicovolcanoconiosis (alt. -koniosis), a factitious word alleged to mean "a lung disease caused by the inhalation of very fine silica dust" but occurring chiefly as an instance of a very long word