It's essentially a tongue-in-cheek way of saying "long-worded" or "using long words".
Here's how the word breaks down:
* Hippopotomonstrosesqui - This part is a play on the Greek word "hippopotamus" and the word "monster".
* Pedalian - This part comes from the Greek word "pedion" meaning "foot", implying a long word that "stretches out like a foot".
So, while it's not a word you'd use in everyday conversation, it's a fun and descriptive word for those who love to use big words or are fascinated by the English language!