Are you refering to the glossary function or the html linking (insert web link) function?
I use the html linking icon on a regular basis. The reader needs to understand that anything in
blue is a link, at least that is true on my Moodles. Sometimes you have to be a little bit more
LOUD I do this with the background color icon, change the font and bold and then add the web link.
(Note: Interesting that the word blue above is underlined and in blue in the edit mode, but the reader only sees it as blue in this forum post. I don't use my reading glasses when I work on my computer and often miss the links. Remember 3-8% of all males have some sort of color blindness. I take the time to at least bold the linked text.)
To link a phrase means blocking the phrase with your mouse, selecting the insert web link icon (next to the anchor), and pasting the link.
You can do a whole paragraph. That is it for web linking. See also
http://docs.moodle.org/en/HTML_editor
I am not a big time glossary user. But I think you can add a phrase in your course glossary. When the reader sees the phrase in your lesson (glossary makes certain words highlited in our forums - grey for me), a click on it will take them to the explaination located in the glossary you created. Go here to start learning about glossary
http://docs.moodle.org/en/Glossary Hope this helps.