Ebook readers that have dictionaries include: the Barnes and Noble Nook, Kindle 2, Sony PRS-900, 600 and 700, and the Kindle DX. You can get dictionaries on a few other ebook readers but it requires some hacking and or technical workarounds.

Ebooks for the Kindle are not always cheaper than Sony’s. For people who live outside the US Kindle’s ebooks cost $2-4 more than other major ePub ebook retailers that sell bestsellers for $9.99.

Not all Sony’s have a dictionary. The touchscreen models do, and it’s really easy to use; you just tap on the word with either your finger or the stylus.

With the Kindle it’s a bit more tedious because you have to move the cursor across the screen to the word you want to look up.