If a right-click will do, you can put the macro on the context menu.
Then have that macro look up Selection.Words(1) in your dictionary/database,
and display the definition somewhere (status bar, message box, toolbar,
...).

If you want mouse-over, you'd need a smart tag recognizer, and would have to
update to Word2003.
The Research pane should also be a good interface for your task (Alt+click
on the word), though I haven't used or programmed it yet.

Regards,
Klaus

G'day "Instructional Designer" <Instructional
Designer@discussions.microsoft.com>,

I have a feeling this can be done from an old WordBasic command, try
the links from the mvp site:

http://word.mvps.org/FAQs/index.htm

Steve Hudson - Word Heretic

steve from wordheretic.com (Email replies require payment)
Without prejudice

"Instructional Designer" <Instructional
Designer@discussions.microsoft.com> reckoned: