Glossary uses the same Greek root.
Glossophobia is the fear of public speaking which was mentioned in the question. This word is composed of the Greek γλῶσσα (glōssa), meaning "tongue," and φόβος (phobos), meaning "fear."
Glossary starts with the same root glōssa, because in the Middle Ages, a "gloss" was an explanation of a rare or foreign word (which comes close to today's glossaries).
