I'm not sure about BN books, I would think you could use the look up feature on all of those. But I have had some library books that I couldn't use the feature. I'm not sure if it works with library EPUB and possibly not with library PDF's. Most likely it was just something with that book.
I've also noticed on some library books that I can't change the font or background color.
So far every BN book has been fine though.