I learned the word antidisestablishmentarianism as a kid because it was fairly easy to learn for a big word. But it's only 28 letters long, far from the longest in the English language. How about 45 letters? Try pneumonoultramicroscopicsilicovolcanoconiosis. There are longer words, but they are chemical names that dictionaries don't count. Pneumonoultramicroscopicsilicovolcanoconiosis is a disease of the lungs caused by inhaling fine dust from quartz or a fine silicate. In real life, doctors call it silicosis. I can't blame them. If you want to pronounce it, it's doable by breaking it into its many Latin parts, pneumo no ultra microscopic silico volcano con iosis. You may think that someone was trying to be funny by slipping "volcano" in the middle, and you'd be right. The word was coined by the then-president of the National Puzzlers' League in 1935. But it turned out to be a useful word for pulmonary doctors, so here we are. And I am thankful for the copy/paste function.
Learn more about pneumonoultramicroscopicsilicovolcanoconiosis and some other very long words from the English dictionary, including one with 36 letters that means the fear of long words. Appropriate. -via Damn Interesting
(Image credit: DataBase Center for Life Science (DBCLS))