moderator

American  

[mod-uh-rey-ter] / ˈmɒd əˌreɪ tər /

noun

1. a person or thing that moderates.

2. a person who presides over a panel discussion on radio or television.

3. a member of an online message board or electronic mailing list with privileges and responsibilities to approve or reject messages and uphold the terms of service.

4. a presiding officer, as at a public forum, a legislative body, or an ecclesiastical body in the Presbyterian Church.

5. Physics. a substance, as graphite or heavy water, used to slow neutrons to speeds at which they are more efficient in causing fission.

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moderator British  

/ ˈmɒdəˌreɪtə /

noun

1. a person or thing that moderates

2. Presbyterian Church 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

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moderator Scientific  

/ mŏd′ə-rā′tər /

1. A substance, such as graphite, water, or heavy water, placed in a nuclear reactor to slow neutrons down to speeds at which they are more likely to be captured by fissionable components of a fuel (such as uranium-235) and less likely to be absorbed by nonfissionable components of a fuel (such as uranium-238).

2. Also called neutron moderator

3. See also slow neutron

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Other Word Forms

• moderatorial
  adjective
• moderatorship
  noun

Etymology

Origin of moderator

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

Explanation

Someone who oversees a meeting, debate, or discussion is called a moderator. It's the moderator's job to make sure that none of the candidates go over their allotted time when they answer debate questions. A debate moderator has an important job, asking questions, maintaining order, and cutting off speakers when they're officially run out of time for a response. In a meeting, a moderator has similar tasks, ensuring that everyone gets a chance to speak — but not for too long. Online moderators can delete threatening, vulgar, or spam messages, and they also make sure discussions stay on topic. Moderators can also be more like mediators, negotiating disputes and helping people reach agreements.

Example Sentences

Moderator Julie Watts noted that California home insurance rates are below the national average and questioned the legality of a freeze.

From Los Angeles Times • Apr. 29, 2026

Moderator Linsey Davis set him straight on that — not that he'll ever stop saying it.

From Salon • Sep. 11, 2024

Moderator Megyn Kelly: She let the candidates argue with each other more than other hosts at other debates.

From Washington Times • Dec. 6, 2023

Moderator Hugh Hewitt went to each candidate with his notion that the American naval fleet was too small, and wanted to know just how many ships each aspirant intended to build.

From Slate • Nov. 9, 2023

If the Moderator asked her that, Telzey thought, she could feel she'd made a beginning at getting him to buy the whole story.

From Novice by Schmitz, James H.

Related Words

• mediator
• referee