pneumonoultramicroscopicsilicovolcanoconiosis
[noo-muh-noh-uhl-truh-mahy-kruh-skop-ik-sil-i-koh-vol-key-noh-koh-nee-oh-sis, nyoo-] noun

an obscure term ostensibly referring to a lung disease caused by silica dust, sometimes cited as one of the longest words in the English language.