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

According to court documents, Szabo was the organizer and moderator of chat groups formed in 2020 where the conspirators communicated with one another.

From Barron's • Apr. 29, 2026

Llamas made his way from the hotel to the NBC News bureau with “Meet the Press” moderator Kristen Welker and veteran Washington correspondent Andrea Mitchell.

From Los Angeles Times • Apr. 26, 2026

Ferreira’s Margot, the new film’s gutsy, likable lead, is a content moderator for a social media site named Kino.

From Los Angeles Times • Apr. 9, 2026

He played moderator for a panel of power players: former UK Prime Minister Tony Blair, King Abdullah II of Jordan, and then-Secretary of State Condoleezza Rice.

From BBC • Feb. 26, 2026

Martha Ackmann served as moderator and, along with the eight women who could attend, told the story.

From "Women in Space" by Karen Bush Gibson

Related Words

• mediator
• referee