Is pneomonoultramicroscopicsilicovolcano... the longest word in english?

You're likely thinking of pneumonoultramicroscopicsilicovolcanoconiosis, which is often cited as the longest word in the English language.

However, it's not officially recognized by any major dictionary as a word. It was coined in 1935 by American physician, Dr. Everett M. Smith, as a humorous example of a long word, not as a legitimate word.

While it's an interesting and memorable word, it's not officially considered a real word. There are other very long words in the English language, some of which are actually used in everyday speech.