I've seen it suggested (http://moodle.org/mod/forum/discuss.php?d=27927) that a separate group be made for each student... but unfortunately I don't know how many students there are going to be. This is mean to be for a 'fire and forget' kind of course.
With many thanks,
The only way I can see is to use groups, but obviously this will not work in your situation. So perhaps forget about the glossary module and use an online assignment instead, with no forced due date and allowing resubmission.
You won't get the features of the glossary (auto-linking, display formats,etc.) but you will automatically get something that only the student and you can see. It is then down to the student to lay out the glossary in a way that suits them.
Just a suggestion, hope it works for you.
Thus, once student adds an entry, it will be in the "unapproved" status and will remain invisible to the whole class, except course instructor.
We did the same for the Database tool.