You can define which users can add new community terms and set moderation authorizations for added terms. Once set, all new terms will appear as drafts in your Glossary list of terms, and will only show on site once you approve them.
Both anonymous and registered users can add new glossary items directly. Word or phrase suggestions, when added by a visitor, appear in the Glossary Terms list as a draft. The “New Community Terms” Add-On is compatible with all the Pro & Pro+ Editions, as well as the Free Edition!