I just updated to iOS 9, and I noticed that the built-in dictionaries, I previously used, aren't working. I had used American English, British English, and Apple Dictionary. Now, when I try to define any word, I get a "No definition found" error. The dictionaries I previously used show a blue circle (while all the others show the cloud download icon).
I was so sad when this happened to me because I practically have no vocabulary😂 It's an easy fix though you go to settings->general->reset->reset keyboard dictionary.
Trust me it won't do anything bad. I freaked out when I saw you have to reset it but you only have to reset the dictionary keyboard to work. A plus is that it still has your dictionaries downloaded and ready to go after you've reset it😊