MacOS – Native OSX Dictionary

The only way I could get this to work is by creating a new service that looks up the word and than tells Dictionary.app to use the "all" filter.

1. Open /Applications/Automator.app and select the services template
2. in the top right part of the screen, you should see that the default input parameters Automator has selected ("Service receives selected text in any application") is just what you want
3. in the left hand search field, search for an Action called "Run Applescript" and drag it into your workflow

4. replace the part "(* Your script goes here *)" with the following Applescript, and than choose File->Save. Automator will ask you for a name for your new service (eg. "lookup in all dictionaries" and from that moment on, your service will be available in all applications.

   set dictLocation to "dict:///" & input
   open location dictLocation
    tell application "System Events" to tell process "Dictionary" to keystroke "0"    using command down
   

5. (optional) You might also want to define a shortcut for you new service by going into "System Preferences">"Keyboard">"Keyboard Shortcuts">"Services", finding your Service in the list of Services, and double-clicking the whitespace next to it do define a global shortcut.

Cocoaspell is an open source dictionary. Cocoaspell is a MacOSX interface to Aspell.

Aspell is an Open Source spell checker designed to eventually replace Ispell. Its main feature is that it does a much better job of coming up with possible suggestions than Ispell does. In fact recent tests shows that it even does better than Microsoft Word 97's spell checker or just about any other spell checker I have seen. It also has support for checking (La)TeX and HTML files, and run time support for other non English language.