While this workaround is definitely not as efficient as the Ctrl Command D command in Safari, here’s what I do.

I have the Dictionary.com search bar plugin installed in Firefox. If I want to search for a word I double click it and hit Apple C to copy the word to the clipboard. I then hit Apple T to open a new Firefox tab. Now I hit the tab key to put the keyboard focus in the search bar. Now hit Apple V and then enter and the word will be looked up at Dictionary.com.

If you’re used to the simplicity of the Safari Dictionary method this will seem complex and ugly. But it works…

This is a nice hint, but it still requires that you type a URI into your browser. An earlier followup pointed out that Cntl-Cmd-d does the job automatically, but that only works in Cocoa apps (and frankly I’ve found it to be a bit spotty — sometimes it works, sometimes not). If, however, you are partial to Firefox or any other non-Cocoa browser (though this will work in Cocoa browsers as well, of course), you can get almost the same functionality with a little javascript. Specifically, create a bookmark called “Dict” and for the location enter:

javascript:x=escape(getSelection());if(!x){void(x=prompt(’What should I look up?’,”))};window.location=’dict:///’ x

Stick that bookmark on your Firefox toolbar. Now you can call up (a running copy of) Dictionary.app for a definition of a word you come across while browsing just by highlighting it and clicking on your new bookmark. (Just clicking on the bookmark without highlighting anything will bring up a dialog box in which you can enter a word manually.)

Note the same trick can be used to call up Google for definitions. In this case, create a bookmark called “GoogleDict” (or whatever) and use the following code for the location:

javascript:x=escape(getSelection());if(!x){void(x=prompt(’What should I look up?’,”))};window.location=’http://www.google.com/search?query=define:’ x

More generally, you can alter this code to do a search on any site with a searching mechanism — Wikipedia, Amazon (nice for looking up highlighted book titles or authors), whatever. Just go to the site in question, enter a search string, and use the resulting URI as the basis for revising the javascript to define the location of a new bookmark for searching that site. Just replace the specific search string you used with “x” in the javascript, as that is the variable that is carrying the string that you’ve highlighted.

BTW, I did not invent the basic code here. I’ve been using it for so long I don’t remember where I found it, but it is quite likely that I saw it in a MacOSXhints hint!

Source: MacOSHints.com

If I run across a plugin I’ll be sure to let you know :)

http://haoli.dnsalias.com/Saft/