Moderator
Moderator , noun
[Latin: compare French modérateur.]
1.
One who, or that which, moderates, restrains, or pacifies. — Sir W. Raleigh
Angling was... a moderator of passions.
2.
The officer who presides over an assembly or discussion to preserve order, propose questions, regulate the proceedings, and declare the votes.
3.
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.
4.
A mechanical arrangement for regulating motion in a machine, or producing equality of effect.