Why can't I define words when I'm offline?

If you can't define words when you're offline, it could be one of a few things:

• You haven't installed an offline dictionary yet.
• Libby doesn't recognize the installed dictionary yet. To resolve, close Libby completely, then re-open it. Then, you should be able to define words while offline.
• The offline dictionary you're using isn't compatible in Libby. Unfortunately, this means you'll need to try another one, like a Livio offline dictionary (in various languages), ColorDict, or Dictionary.com.