0 a name that has been invented for a lung disease caused by breathing in very small pieces of ash or dust: --
Pneumono refers to the lung. Ultra means extremely, microscopic means tiny, silica is sand, volcano is self-evident, and coniosis is scarring. Put them all together and you have what the OED recognizes as the longest word in the English language, pneumonoultramicroscopicsilicovolcanoconiosis.
