For those losing hairs over how to set up a dictionary (e.g. Chinese) other and default English, here is how I managed to get things working on iPad iOS6 and iBooks 3. There is no need to switch the system language to Chinese
. Before continuing, ensure you have WiFi connection.
1. Look for a free Chinese ebook (ePub format) and upload it to your Dropbox folder.
2. Use iPad Dropbox app to access the Chinese ePub book just uploaded.
3. Use the Open-in function in Dropbox to open the ePub book (the icon on the top-right corner of Dropbox app).
4. Choose the Open in IBooks icon. This will copy of the ePub book to your IBooks local bookshelf on your iPad.
5. Once the ePub book is opened in iBooks, highlight a Chinese word to look-up in the dictionary (Choose "Define" to look-up word in dictionary).
6. At this point, iBooks will prompt "Would you like to download a dictionary now?" - This being that the word in not in the local dictionary yet. If it does not prompt you, look for another ePub book.
7. Click on "Download Dictionary". If your WiFi is not turned on, it will prompt you to do so.
8. Watch the download progress bar in action. It maytake a minute or two depending on your WiFi connection speed.
9. When the download is completed, the Chinese word highlighted earlier in the dictionary is displayed - Voila!
In this case, the dictionary downloaded is a Chinese-Chinese dictionary. Good thing is that the PinYin is shown in the look-up to help in reading the word.
To search for a Chinese-English translation, click on "Search Wikipedia" in display box of the dictionary. It will look up the word in Wikipedia. If this word is not found in Wikipedia and then click on "Wikitionary" form the list of sister projects (listed on the right-side of the page).
Voila again! You now have the word defined in Wikitionary, with explanation in English, pronunciation in Mandarin and other useful information.
I believe all of the above also works for other languages besides Chinese!
I have got screen grabs of the steps successful captured as well.
Best of luck for your attempts with other languages dictionaries.