Foreign language dictionaries on devices

I read a lot of books in French, German and Italian. I am thinking it would be very convenient to look up unknown words on my phone but the simple dictionary I downloaded does not have most of them. Which platform would have the most comprehensive dictionaries available for translating the words that you may get in 19th century novels into English as this would be the most important factor in my choice of a new device?

I would be grateful to anyone who has experience and recommendations in this area.

On the Kobo I've found that the translation dictionaries they supply are next to useless (they only contain words I already know). The Spanish single-language dictionary works well for me, but of course it's a bit less convenient to have to decipher a definition in Spanish when you want to know what the word means in English. The French and Italian dictionaries don't seem to be quite as comprehensive as the Spanish one, and they aren't as good at stemming and finding the right headword, but I did manage to get through La Chartreuse de Parme in French last year...
I hardly ever bother to look things up in German, so I can't comment on that one.
A recurrent nuisance on the Kobo is that many ebooks you buy from their store don't have the language set, so you get the wrong dictionary popping up. I found that the easiest workaround for that was to change the interface language to the language of the book.

If you are the sort of person who doesn't feel comfortable guessing what strange words mean, you probably won't be satisfied with whatever public-domain dictionary comes bundled with an e-reader. Internet access and a web-browser give you a lot more possibilities (think about things like TLF for French).

That's very useful to know thank you. Funnily enough I didn't quite finish La Chartreuse de Parme, perhaps a dictionary would have helped, but I found it too picaresque and rather cold.

I downloaded 'offline dictionaries' on android. There's a choice of free dictionaries (translation as well as single language) that may not have all words but that have nevertheless served me well in English, German and French. YMMV