As I understand it - at the present time there is a choice of American English and British English. period. So, yes, you can change the dictionary's language from English - to English!! There is no other available language dictionary that can be used as a "built-in"...meaning the word definition comes up after tapping on the screen. I'm sure Sony must have French, German, Spanish in the works, as they are rolling out in Europe next year, but those are not presently available.
That said, French/Geerman etc texts with accented characters display perfectly, and you can input accented charcters by means of the virtual keyboard (takes some flipping through screens) AND there are foreign language reference works you can load. Looking up a word takes more time - because you would have to open the reference work, type in the word to be looked up, use Search, then go back to Home and re-open the book you were reading.