Did you know that you can trigger Apple’s built-in dictionary in almost any system window, such as TextEdit, Safari, and Mail? This allows you to quickly get spelling and definitions for tens of thousands of words. If you are reading this blog post in Safari, using OS 10.4, hold down the command-control-d keys, all at the same time with your mouse over a word (the command key is the Apple key, next to the space-bar.)
The built in dictionary will pop up, as pictured below. Again, this will only work in OS X system programs, not in third party programs like Firefox or MS Word.
I discovered this by accident; I wonder what other cool and useful shortcuts are hidden in OS X?
THIS IS WHAT THE BUILT IN DICTIONARY SHORTCUT LOOKS LIKE: