If you're not looking for the full updated Wikipedia dataset, you can just use StarDict with a few downloaded reference files: I run the Britannica Concise encyclopaedia, the CIA World Fact Book, and a basic dictionary. I also have a Eng-Japanese dictionary installed. There are lots more to choose from. All in all, it's compact, easy to set up, and works well enough when I'm off-line, even if the files are a few years out of date.

David...