The word Pneumonoultramicroscopicsilicovolcanoconiosis is defined as "a lung disease caused by the inhalation of very fine silica dust, mostly found in volcanos". It was originally postulated by Everett M. Smith, simply to serve as the longest English word, but has been used in several sources as an approximation of its originally intended definition. The plural of this word, pneumonoultramicroscopicsilicovolcanoconioses is equally long.
