The Define Word plugin (which started as a bit of an experiment) is now actually a useful one! Based on several comments, suggestions and code snippet contributions, I have made several changes and you can now download Define Word 0.5.0.
In this version:
* The list of search engines is dynamic and can changed using the Options dialog,
* Your preferred search engines show up in the pop-up menu so you don’t have to change the settings to use another one,
* The pop-up menu now also appears inside text entry fields,
* The default list of search engines has been extended to include acronymfinder.com, hyperdictionary.com, dict.die.net and several others.
* Define Word supports FireFox v1.0 on all platforms, but older versions are no longer supported. The full Mozilla browser is also not supported.
Thanks for all your comments and feedback!