I would like to change the dictionary my iPhone uses for defining words (not for spell-checking) to a learner's one (e.g. Cambridge). Apple provides several dictionaries for various languages, but not an English Learner's one. Any idea how I may make a non-Apple dictionary the default?
There is an application in the App Store named Dictionary Appender. You can import dictionary files into the application via iTunes file sharing (on your computer) and install them in Dictionary Appender (on your iPhone). Then your iPhone will use your selected dictionary when you mark some text and choose