The description doesn't tell you, but it doens't work as a reading dictionary on eg Fire HD, because you can't make it a default for reading. So very very disappointed. I haven't found any way to install it as an option along with the preinstalled dictionaries, so that I can read in French and click on words for instant transalation (which is why I bought this dictionary).
Does anyone know of doing it? I've trawled the web. I really do not want to break my reading flow book to consult the web or a separate book or app. This promised all and failed to deliver.