Actually, you don't need to open dictionary application each time you want to check the definition of a word. You can use this :
Quick Dictionary
Snapshot above is taken when I looked up a word definition in dictionary. What I have to do is I just need to put my pointer above certain word then I pressed 
D
Customizing Keyboard Shortcuts
If you looked inside System Preferences ▸ Keyboard & Mouse ▸ Keyboard Shortcuts, there will be a long list of keyboard shortcuts. These all shortcuts can be customized by Double-Clicking on top of the shortcut symbol and filling in new keyboard shortcut.
Here is all the keyboard shortcuts that can be customized inside :
| 1 | Toggle Front Row | Cmd-Escape |
| 2 | Quick Dictionary | Cmd-Control-D |
| 3 | Help | Cmd-Shift-Slash[/] |
Screen Shots
| 4 | Snap Whole Screen | Cmd-Shift-3 |
| 5 | Snap Whole Screen to Clipboard | Cmd-Control-Shift-3 |
| 6 | Snap Certain Area | Cmd-Shift-4 |
| 7 | Snap Certain Area to Clipboard | Cmd-Control-Shift-4 |
Zoom
| 8 | Activate Zoom | Cmd-Option-8 |
| 9 | Image Smoothing | Cmd-Option-Backslash[\] |
| 10 | Zoom Out | Cmd-Option-Hyphen[-] |
| 11 | Zoom In | Cmd-Option-Equal Sign[=] |
Contrast
| 12 | Increase Contrast | Cmd-Option-Control-Period[.] |
| 13 | Decrease Contrast | Cmd-Option-Control-Comma[,] |
| 14 | Invert | Cmd-Option-Control-8 |
| 15 | Toggle VoiceOver | Cmd-F5 |
| 16 | Toggle Full Access | Control-F1 |
Move to
| 17 | Menu Bar | Control-F2 |
| 18 | Dock | Control-F3 |
| 19 | Next Active Window | Control-F4 |
| 20 | Toolbar | Control-F5 |
| 21 | Floating Window | Control-F6 |
| 22 | Text Boxes and Lists | Control-F7 |
| 23 | Menu Bar Status Menu | Control-F8 |
| 24 | Other Window within Application | Cmd-Accent[`] |
| 25 | Window Drawer | Cmd-Option-Single Quote['] |
| 26 | Toggle Character Palette | Cmd-Option-T |
Dock, Expose, and Dashboard
| 27 | Hide/Show Dock | Cmd-Option-D |
| 28 | Show Spaces | F8 |
| 29 | Show All Windows | F9 |
| 30 | Show Application Windows | F10 |
| 31 | Show Desktop | F11 |
| 32 | Show Dashboard | F12 |
Spotlight
| 33 | Search Field | Cmd-Space |
| 34 | Window | Cmd-Option-Space |
Display
| 35 | Decrease Brightness | F14 |
| 36 | Increase Brightness | F15 |
These shortcuts haven't received much changed compare to Mac OS X Tiger. Only Front Row, Quick Dictionary, and Spaces are considered new on Leopard.
COMMENTS
Jay
November 26th, 2007 at 03:27 AM
Great tip that should be shouted from the roof tops. Thank you usingmac.com.
kambizpascia
November 29th, 2007 at 06:16 PM
great blog thank you In fierfox dont work ctrl+mac+D ?
nick
November 29th, 2007 at 11:43 PM
I second that the quick dictionary command doesn't work in Firefox (2.0.0.10)
Isaac
December 5th, 2007 at 04:29 AM
Quick Dictionary and the Front Row shortcut were both in tiger. They are not new to leopard. There was even a quick tip video for quick dictionary months before leopard was released. Thanks for the collection of shortcuts. bookmarking.
Melina
December 21st, 2007 at 03:07 AM
very interesting. i'm adding in RSS Reader