I have many documents, and I'd like to be able to change a style definition for all of them. For example, I want the "Heading 3" style in all the documents to change so that it is now underlined. Is there any way to avoid changing the style in all the documents? Is there a way to have each document share a common style definition template? If Word can't do this, is there some other word processor that can?
This would be analagous to how multiple html pages can all refer to the same cascading style sheet. In Word, I guess the way it would work would be something like this: whenever the document is opened, Word would look for the shared template where the styles are defined, and render the document according to the styles it finds. If it couldn't find the shared template, I'm not sure what would happen - maybe it'd revert to the style definitions in the document itself, or in the Normal template or something.
I'm using Word 2003.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic