Look into AutoText or some other Building Block as a storage receptical for your tagged terms to insert them into other documents.
Automated Boilerplate Using Microsoft Word

If you want the definition as a mouse-over pop-up look at my free-download using the AutoTextList field to pop up text. Pop-Up Text Add-In for Microsoft Word
That has a limit of 255 characters for the definition, though. This is similar to one of the methods described in one of the TechRepublic articles but does not use the HyperLink field.



Lene Fredborg has code for using the Hyperlink field and an Add-In that allows for more text than 255 characters. Add Screen Tips to Text in Word by Lene Fredborg, MVP

These could also be saved as AutoText or Building Blocks for easy insertion. I would recommend using names that are related to the terms but not the same as the terms. i.e.
Items stored as AutoText or Building Blocks could be used in a BB Gallery Control which could be on the Ribbon or in a QAT entry.
Build & Deploy Custom Building Block Galleries by Greg Maxey

If you are doing document assembly, you may also want to look at Boiler - Insert a selection of documents by Graham Mayor, MVP