Is there a site that tell what all the long words are in a food label??

Here is a site that lists additives. Up at the top of the page you'lll find additives. Just click on that and a pull down menu comes up. You can get numbered and other additives. It doesn't give descriptions for all but for most.

Foodag

carr,

This one looks interesting, as well.

Food Additives

Here's more Carr,

Food & Ingredient Glossary

Also check out the book,

A Consumer's Dictionary of Food Additives