What is the longest REAL word you know?

antidisestablishmentarianism

And no, you can't pluralise it!

The longest word in any of the major English language dictionaries is pneumonoultramicroscopicsilicovolcanoconiosis, a word which refers to a lung disease contracted from the inhalation of very fine silica particles, specifically from a volcano. Research has discovered that this word was originally a hoax; medically, it is the same as silicosis. It has since been used in a close approximation of its originally intended meaning, lending at least some degree of validity to its claim

Pneumonoultramicroscopicsilicovolcanoconiosis- A lung disease caused by inhaling silica dust.

pseudocryptoantidisestablis hmentarianists

(I've added a space to circumvent that STOOP-IT yahoo limit to the number of characters it will display in a word)

This word refers to people who pretend to secretly support antidisestablishmentarianism, but in reality don't.