moderator
noun
[ ˈmɒdəreɪtə ]
• an arbitrator or mediator.
• "Egypt managed to assert its role as a regional moderator"
• a person who reviews examination papers to ensure consistency, or otherwise oversees an examination.
• "after marking by the tutor, the papers are returned to a moderator"
• a person who moderates an internet forum or online discussion.
• a substance used in a nuclear reactor to retard neutrons.
• "in a fast reactor there is no moderator to slow the reaction down"
