What is pneumonoultramicroscopicvolcanoconiosis?

Answer 1

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 found in volcanoes' but occurring chiefly as an instance of a very long word."[1] It was coined to serve as the longest English word. It is one of several several dust inhalation lung diseases called pneumoconeoses. Pneumonoultramicroscopicsilicovolcanoconiosis (also spelled -koniosis) 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 found in volcanoes' but occurring chiefly as an instance of a very long word. It was coined to serve as the longest English word. The more general and widely used term for this condition is pneumoconiosis. From Reference.com