I believe the word is French and means boil in bag - it is a style of cooking. -- oops, it is French but means under vacuum

The bags I buy for my vacuum packer are labled as usable in that type of cooking - aka boil in the bag.

I'll see if I can find a link online. --http://en.wikipedia.org/wiki/Sous-vide

I believe the zip lock style freezer bags release "bad" for us chemicals when boiled.