What is a 10 syllable word?

There are no 10-syllable words in the English language. The longest word in English, with 45 syllables, is "pneumonoultramicroscopicsilicovolcanoconiosis," which refers to a lung disease caused by inhaling very fine silica dust.

If you're looking for words with a specific number of syllables, it's helpful to use a dictionary or online tool that allows you to search by syllable count.