I decided to give it a shot. I found some useful resources that you can use, should you decide to make your own. I made an extension that will define the currently selected word and open it in a new tab.
Here's how to install it:
Go to where you downloaded it
Change the .zip to .xpi
Go to Tools->Add-ons
Drag the file into the Add-ons window
Allow the add-on to install
Now, all you have to do is select a word, right click, and select "Define Selected".
This is my first attempt at a Firefox extension. Should you have any issues with it, please let me know. I'll see what I can do. I had to change the extension because the forum won't allow .xpi (Note: Firefox extensions are actually ZIP files, anyway)
Edit: Whoops...forgot to add how to change the file extension.
Assuming you have never had to change an extension, Windows will hide known file extensions. Setting it to show them is quite easy. Here's how (using the Classic Control Panel view):
Go to the Control Panel (Start->Control Panel)
Double-click on Folder Options
Go to the View tab
Uncheck "Hide Extensions for Known File Types"
After that, it will show all file extensions. You will then be able to do step 2 in the installation instructions.
Also, note that, while I do believe that this add-on is perfectly safe to install, you are doing so at your own risk. I take no responsibility whatsoever if this extension (some how) messes anything up. I've been testing it a lot, and it appears to be functioning perfectly, so there should be no need to worry.
Last edited by X-626; February 15th, 2009 at 12:03 AM.
Reason: Forgot to add how to change the file extension