noun one who, or that which, moderates, restrains, or pacifies.
2. moderator ·noun a mechamical arrangement for regulating motion in a machine, or producing equality of effect.
3. moderator ·noun the officer who presides over an assembly to preserve order, propose questions, regulate the proceedings, and declare the votes.
4. moderator ·noun in the university of oxford, an examiner for moderations; at cambridge, the superintendant of examinations for degrees; at dublin, either the first (senior) or second (junior) in rank in an examination for the degree of bachelor of arts.