It's just not practical, therefore we try to include at least a few and place the best uses towards the top.

As an example, take the word irresolute. Although we provided five uses of the word, we know that irresolute is also used in War and Peace, Wuthering Heights, Moby Dick, Uncle Tom's Cabin, Treasure Island, Frankenstein, The Adventures of Tom Sawyer, The Count of Monte-Cristo, Jane Eyre, Ulysses, and over a dozen other titles that we are aware of. This may be an extreme example as irresolute is (what we call) a core vocab word, but it illustrates the point.

The “uses” button is greyed-out when the word is not in that vocabulary collection. If we believe the word is in a selected book, then the “uses” button will have a black border. This makes it possible to click through different book titles on the side menu and quickly ascertain whether that vocabulary word is in that collection.

lassitude is not in our Anna Karenina vocabulary collection.

lassitude is used in Orwell's 1984.

Remember that we do not necessary show every vocabulary word use for every title, but if we claim a word is in a book, then it is probably in that book (or at least some form of that word).