[Rob Lister]

I can't speak to the question of rooting but the dictionary works like this: when the definition for a word opens, it does so in a pop-up window on top of the page you're viewing. Very unobtrusive. It can then be dismissed by clicking the X in the upper right corner of that pop-up.

The dictionary on mine (here in the U.S.) is Merriam-Webster's Collegiate Dictionary. I would think that Nooks sold in other countries would have dictionaries native to that country's language or usage thereof ... but I suppose that depends on business and licensing relationships.