To remove everything except for the entry definition itself from your glossary popup window add this CSS declaration at the end of one of your theme's CSS files:
#mod-glossary-showentry #header,
#mod-glossary-showentry .navbar,
#mod-glossary-showentry .concept,
#mod-glossary-showentry .helplink,
#mod-glossary-showentry a {
display:none;
visibility:hidden;
}
Please note that this will also hide away any link (e.g. to external site) present in your glossary entries. If you need to display them, then remove from above this line:
#mod-glossary-showentry a
See result in attached screen shot.
However, in that case, the link to the Glossary itself will be displayed in the Glossary entry window. There is unfortunately no way to remove that for the moment.
Joseph
PS.- I don't see any glossary in Course Biblical Greek I on your site. Where is it?