Adding Reference Libraries

By default, your dictionary's reference libraries shown are Wikipedia, Dictionary, Thesaurus and Apple. Obviously, you can add more references to it.

First, go to your Dictionary Preferences Pane by either using keystrokes [,] or using menu bar Dictionary ▸ Preferences. Then you will see there are more than four default references which is available for your Dictionary.

You also need to pay attention that the change will take effect only after you've closed the Preferences Pane.

Calling Dictionary Right from Browser

If you're in the mood of using your mouse, you can use keystrokes D to call see the definition of a word; You can see Leopard - Quick Dictionary for more details.

However, if you're not thinking of using your mouse, you can move your cursor to your browser url bar (L) and then type dict://apple, which apple is the search term. For your surprise, your Dictionary will be triggered.