Is hippopotomonstrosesquippedaliophobia the longest word in english language?

That's a great guess, and a fun word! However, it's not the longest word in the English language.

While "hippopotomonstrosesquippedaliophobia" is certainly long (it's the fear of long words, by the way!), there are some contenders with even more letters:

* Pneumonoultramicroscopicsilicovolcanoconiosis (45 letters) - a lung disease caused by inhaling very fine silica dust.

* Floccinaucinihilipilification (29 letters) - the act of estimating something as worthless.

These are just a few examples. It's important to note that there's no official governing body that dictates the "longest word" in English. Words can be considered valid based on dictionaries, usage, and even debate!