Weblog MacApper details how to set up Quicksilver as a quick and universal dictionary lookup tool. The step-by-step covers everything from installing the Dictionary plug-in to assigning a universal trigger that can define the currently highlighted word. The trigger isn’t necessary, of course, since you can also get definitions by typing the word into Quicksilver and selecting the Dictionary action. In fact, when you install the Dictionary plug-in, you also get a Thesaurus plug-in to boot. I’ve been using Quicksilver as my primary dictionary ever since I got my Mac, and it’s definitely the quickest way I know to perform a fast lookup.