moderator

UK: /ˈmɒdəreɪtə^r/ US: /ˈmɑdəˌreɪtɚ/ ,(mod′ə rā′tər)

WordReference Random House Learner's Dictionary of American English © 2025

mod•er•a•tor /ˈmɑdəˌreɪtɚ/   n. [countable]

1. a person or thing that moderates.
2. Show Business a person in charge of a group event or meeting:
   As the moderator he decides who speaks and for how long.

See -mod-.

WordReference Random House Unabridged Dictionary of American English © 2025

mod•er•a•tor  (mod′ə rā′tər), n. 

1. a person or thing that moderates.
2. Show Business a person who presides over a panel discussion on radio or television.
3. a presiding officer, as at a public forum, a legislative body, or an ecclesiastical body in the Presbyterian Church.
4. Physics a substance, as graphite or heavy water, used to slow neutrons to speeds at which they are more efficient in causing fission.

• Latin moderātor, equivalent. to moderā(rī) to control (see moderate) + -tor -tor
• 1350–1400; Middle English

mod•er•a•to•ri•al  (mod′ər ə tôr′ē əl, -tōr′-), adj.  mod′er•a′tor•ship′, n. 

Collins Concise English Dictionary © HarperCollins Publishers::

moderator / ˈmɒdəˌreɪtə/ noun

1. a person or thing that moderates
2. a minister appointed to preside over a Church court, synod, or general assembly
3. a presiding officer at a public or legislative assembly
4. a material, such as heavy water or graphite, used for slowing down neutrons in the cores of nuclear reactors so that they have more chance of inducing nuclear fission
5. an examiner at Oxford or Cambridge Universities in first public examinations
6. (in Britain and New Zealand) one who is responsible for consistency of standards in the grading of some educational assessments
7. a person who monitors the conversations in an on-line chatroom for bad language, inappropriate content, etc

ˈmodeˌratorship noun