[douxiaobo]

Originally Posted by Doitsu

Mobi dictionaries need to be in a special HTML format. Therefore converting .pdfs will never work unless you reformat the .html file and add the necessary tags. For more information, see the Mobipocket Developer Center.

There are also two free Spanish Kindle dictionaries available, but they're only useful for beginners:
1. Dave Slusher's dictionaries
2. Michael Sheldon's dictionaries

Thanks very much.