Here is a basic video showing how to add a glossary activity in your Moodle course. This video is a part of the Learn Moodle MOOC 2015 based on Moodle 2.8
This video shows how to add a new glossary to your course and add terms into it including some basic settings about the glossary activity.
Glossary activity allows participants to create and maintain a list of definitions, like a dictionary and can be used in many ways like a collaborative glossary, thought for the day and peer assessment etc.
You can also watch all the videos of Learn Moodle MOOOC 2015 from this link: https://youtu.be/129LUmA3z2g?list=PLhL_Pevte7RoS_FvB-7oIsVZhmeGkIS-t