Allows you to define certain key words or phrases which, when used in any of the enable/supported applications, can be hover/clicked over to get a popup with more information which you have defined. This popup can contain whatever content you like, such as term definitions.
Any application that uses the content item class (all of IPS applications work)
Group Settings to add/delete/hide/edit/change/use html author.
Use HTML and BBC in descriptions.
Keywords to URL (use a URL instead of a popup).
Profile Tab to show contributed keywords.
Shows up in activity stream.
Keyword lists with filtering.
Rules App integration (by kevin carwile)
Note: works only with IPS 4.1 (if installed on 4.0, the front navigation will error out). PHP 5.4 minimum (using specific things found in php 5.4+).