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And I can't send any of them to any of my other devices. . .like the Fire or DX or apps that are attached to my account.
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For the Fire, I suspect that's because it hasn't been released internationally yet. The new, broader selection of dictionaries on the basic K4 coincided with its launch (along with localized Kindle Stores) in France, Spain, and Italy. Kindle Fire isn't available in Europe yet, and as far as I can tell Kindle Touch isn't either.
This is my first post as a member, and I was happy to find this discussion. I'm curious--what dictionaries have you found most useful as aids to reading in Spanish on Kindle? Are there any recurring issues you've run into in using foreign language dictionaries on Kindle?
(Full disclosure: my company, Intangible Press, publishes dictionaries for Kindle.)