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[mod-uh-rey-ter] /ˈmɒd əˌreɪ tər/
a person or thing that moderates.
a person who presides over a panel discussion on radio or television.
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.
a presiding officer, as at a public forum, a legislative body, or an ecclesiastical body in the Presbyterian Church.
Physics. a substance, as graphite or heavy water, used to slow neutrons to speeds at which they are more efficient in causing fission.
Origin of moderator
1350-1400; Middle English < Latin moderātor, equivalent to moderā(rī) to control (see moderate) + -tor -tor
Related forms
[mod-er-uh-tawr-ee-uh l, -tohr-] /ˌmɒd ər əˈtɔr i əl, -ˈtoʊr-/ (Show IPA),
moderatorship, noun Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2017.
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Examples from the Web for moderator
Contemporary Examples
Historical Examples
  • For the moderator loved his pipe, and so did I, and together we revelled in those clouds before which all other clouds retreat.

    St. Cuthbert's Robert E. Knowles
  • The moderator had some difficulty in restoring order to the hilarious meeting.

    Cy Whittaker's Place Joseph C. Lincoln
  • The moderator's office had then checked on the sportscar's communication number and attempted to call it.

    Novice James H. Schmitz
  • From Mr. Samuel Price, whom they have spoken of for moderator.

    Coniston, Complete Winston Churchill
  • He then studied theology, and became a pastor, and later superintendent (equal to a Bishop or moderator) near Knigsberg.

    Some Jewish Witnesses For Christ Rev. A. Bernstein, B.D.
British Dictionary definitions for moderator


a person or thing that moderates
(Presbyterian Church) a minister appointed to preside over a Church court, synod, or general assembly
a presiding officer at a public or legislative assembly
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
an examiner at Oxford or Cambridge Universities in first public examinations
(in Britain and New Zealand) one who is responsible for consistency of standards in the grading of some educational assessments
a person who monitors the conversations in an on-line chatroom for bad language, inappropriate content, etc
Derived Forms
moderatorship, noun
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for moderator

late 14c., "ruler, governor," from Latin moderator "manager, ruler, director," literally "he who moderates," from moderatus (see moderate (adj.)). Meaning "one who acts as an umpire" is from 1560s. Fem. form moderatrix attested from 1530s.

Online Etymology Dictionary, © 2010 Douglas Harper
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moderator in Science
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). Also called neutron moderator. See also slow neutron.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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