* "Suf-" comes from the Latin word "sub-" meaning "under" or "below".
* "-fix" comes from the Latin word "figere" meaning "to fix" or "to fasten".
So, a suffix is called a suffix because it's something that is "fixed under" or "attached to the end" of a word.
It's like a little tag or addition that comes *after* the main part of the word, modifying its meaning or function.