Can you use the nook's built within dictionary to look up a word thats not within a book youre reading?

i understand the nook isnt out yet, but maybe someone know more than i do.
the nook has a built in dictionary but can i just use it to look up a word? similar to lets say im in english class and we're doing vocab, can i only turn it on and use the dictionary? or does it have to be in a book im reading?
also while we're on the topic of nooks,
can i buy ebooks using a visa bequest card?
if so can i buy them using it directly from the nook? or can i only use that method of payment on my computer??
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