Is your spelling of pneumonoultramicroscopicvolcanoconiosis correct?

Yes, the spelling "pneumonoultramicroscopicsilicovolcanoconiosis" is correct. It is the longest word in the English language, and it refers to a lung disease caused by the inhalation of very fine silica dust.

However, it's worth noting that the word is rarely used in everyday language and is often considered a novelty or a linguistic curiosity.