Oxford_Advanced_Learner's_Dictionary

Image courtesy of en.wikipedia.org
Good luck trying to pronounce this one…

The longest word in the English language is pneumonoultramicroscopicsilicovolcanokoniosis. Before you start counting and strain your eyes, we’ll give you the facts: It contains 45 letters and 19 syllables. And the definition is almost as confusing as the word: a pneumoconiosis caused by the inhalation of very fine silicate or quartz dust and occurring especially in miners. (Translation: a lung disease.) It was awarded the title “Longest Word in the English Language” based on the simple fact that it is the longest word found in the largest English dictionary, the 20-volume Oxford English Dictionary, Second Edition.