moderator

American  

[mod-uh-ray-ter] / ˈmɒd əˌreɪ tər /

noun

• moderators
  plural

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

Derived Forms

• moderatorship
  noun
• moderatorial
  adjective

Inflected Forms

Nouns

• moderators
  plural

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Etymology

Origin of moderator

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

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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

See Examples For:

moderator moderators

In a reactor, heavy water serves as a neutron moderator, meaning it slows down the neutrons released during fission.

From Science Daily ● Oct. 16, 2026

“Just disgusting behavior by an anonymous account,” Chuck Todd, a former Meet the Press moderator, wrote of the post that mentioned Holmes’ children.

From Slate ● Aug. 18, 2026

Sometimes, Longwell will observe a live feed and suggest questions to the moderator in real-time.

From The Wall Street Journal ● Jun. 13, 2026

Amelia Knox, a moderator for the private Facebook group The Swiftie's Society, is hoping for a reunion between Swift and guests of The Graham Norton Show who starred in her recent Opalite music video.

From BBC ● Jun. 5, 2026

The moderator, a slim guy with hair that looks like it has been glued into place, brushes a speck off his tuxedo, adjusts his red-striped tie, and begins speaking right on cue.

From "Out of My Mind" by Sharon M. Draper

Bass’ barrages got to Raman more than a few times, leading her to talk over the NBC and Telemundo moderators or even shush them.

From Los Angeles Times ● Oct. 14, 2026

Reddit Marketing Agency promises on its website to post comments for clients using “profiles that moderators recognize as legitimate community members” and reduce the visibility of negative comments.

From The Wall Street Journal ● Aug. 14, 2026

Frightened fans and moderators from the social platform were among those who called authorities.

From Los Angeles Times ● Aug. 7, 2026

Teams of human moderators once employed by all the major platforms have been gutted.

From Salon ● Aug. 6, 2026

We met at the appointed time, and chose two umpires to act as moderators of the meeting.

From The Mormon Menace The Confessions of John Doyle Lee, Danite by Alfred Henry Lewis

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Related Words

• mediator
• referee

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