pneumonoultramicroscopicsilicovolcanoconiosis [noo-muh-noh-uhl-truh-mahy-kruh-skop-ik-sil-i-koh-vol-key-noh-koh-nee-oh-sis, nyoo-] noun 1. an obscure term ostensibly referring to a lung disease caused by silicadust, sometimes cited as one of the longest words in the English language. Origin of pneumonoultramicroscopicsilicovolcanoconiosis < New Latin; see pneumono-, ultramicroscopic, silica, volcano, (pneumono)coniosis Contemporary definitions for pneumonoultramicroscopicsilicovolcanoconiosis noun supposedly the longest word in a dictionary, an artificial word said to mean a lung disease caused by the inhalation of silica dust. Word Origin and History for pneumonoultramicroscopicsilicovolcanoconiosis n. 1962, "A facetious word alleged to mean 'a lung disease caused by the inhalation of very fine silica dust' but occurring chiefly as an instance of avery long word " [OED]. Said in an early reference to have been invented byseventh grade students in Norfolk, Virginia. Source