A lot of books have their own very specific type of word usage. Whether it's the Song of Ice and Fire series or Catcher in the Rye, a standard dictionary isn't always enough. The Fictionary fills in those gaps.
A Fictionary is essentially a book-specific dictionary that integrates into your ereader. So, when you select a word to look up a definition, it brings up a definition based on the book as opposed to a classic dictionary definition. For example, look up "the one ring" in The Lord Rings and you'll get a definition from the book, not of just a ring. There aren't a lot of books supported, but it is handy for the handful that are here. Head over to The Fictionary for a list of books and installation instructions.