Titin is the largest protein yet discovered. Its full chemical name is 189,819 letters long and, depending on how you define a “word” is the longest word in the English language.

It is not included in the dictionary – few lexicographers accept chemical formulas as words. But when people go round Googling “What’s the longest word in the English language?”, they don’t really care if it’s a “real” word or not.

Here’s pronunciation: