I am not sure if this is the correct forum to be posting this in, but I'll start here.
The HTML Editor that usually appears in the Description area of the Glossary Settings page is no longer there. It was yesterday, but now is gone... any suggestions?
I doubt that this "disappearing HTML editor" problem would only appear in the Glossary settings.
Can you see the HTML editor when editing other Moodle activities?
Joseph
Joseph is right - this is not caused by Glossary code - you simply have selected Moodle auto-format (in drop-down list under the textarea) and it has not rendered editor (tinymce) in any version of moodle 2.X
Change the format to HTML format, save changes and try editing Description again...