Pneumonoultramicroscopicsilicovolcanoconiosis is the longest word in English. Pneumonoultramicroscopicsilicovolcanoconiosis is a long-term word for "Silicosis". What does Silicosis actually mean? Silicosis is a lung disease that happens when you breathe a tiny particle called a "Silica dust". For more information, just kindly search it up on google.