"hippopotomonstrosesquipedaliophobia" ironically, it means the fear of long words. It originally was referred to as Sesquipedalophobia but was changed at some point to sound more intimidating. Standing at 35 letters and 15 syllables makes it the longest word in the dictionary!

The phobia affects a horrifying 3-15% of the population!

Sources: https://www.verywellmind.com/hippopotomonstrosesquipedaliophobia-2671752 https://psychcentral.com/anxiety/hippopotomonstrosesquippedaliophobia