From the Kindle2" quick start guide"
Using the Built-in Dictionary
While reading a book or periodical, you can see a brief definition of a word using the Lookup feature. The Lookup feature uses The New Oxford American Dictionary.
To see the definition of a word in your reading:
1. Move the 5-way controller up or down to display and place the cursor in front of the word.
2. If the word is found in the dictionary, a definition extract appears at the bottom of the screen.
3. To see the complete definition, press the Return key. You will now be placed in the dictionary and can use Previous Page and Next Page to view other word definitions.
4. Press the Back button to return to your reading.
Choosing your primary dictionary
You can choose the dictionary you want to use when you look up words while you are reading. The default is "The New Oxford American Dictionary" included on your Kindle, but you can change your dictionary choice by purchasing a supported dictionary on the Kindle Store and then following these steps:
1. If you are not already on the Home screen, press the "Home" button.
2. Press the "Menu" button.
3. Move the 5-way controller to underline "Settings" and press to select.
4. Press the "Menu" button.
5. Move the 5-way to underline "Change Primary Dictionary" and press to select.
6. Move the 5-way to underline the dictionary you want to use and press to sele
Here is the link.
http://www.amazon.com/gp/help/custom...deId=200375430