moderator

noun

mod·​er·​a·​tor ˈmä-də-ˌrā-tər 

plural moderators

1

: someone who presides over an assembly, meeting, or discussion: such as

a

: the chairperson of a discussion group

b

: a person who administers an online forum, chat room, or group

c

: the nonpartisan presiding officer of a town meeting

d

: the presiding officer of a Presbyterian governing body

2

: one who arbitrates : mediator

3

: a substance (such as graphite) used for slowing neutrons in a nuclear reactor

moderatorship

ˈmä-də-ˌrā-tər-ˌship 

noun

Synonyms of moderator

• chairperson
• president
• chairman
• presider

Examples of moderator in a Sentence

The moderator allowed audience members to ask the governor questions.

She acts as the moderator in our office meetings.

Recent Examples on the Web

During a panel hosted by sustainability moderator Merle Becker, industry heavyweights explored how the sector’s transformation—from artificial intelligence (AI) and automation to sustainable materials and digital development processes—is becoming a strategic resource. —Alexandra Harrell, Sourcing Journal, 15 Jan. 2026

Just this month, Meghan and Prince Harry made a surprise appearance to speak with authors Jonathan Haidt and Catherine Price about their new book, The Amazing Generation, along with moderator Gayle King. —Stephanie Petit, PEOPLE, 13 Jan. 2026

Friday moderator Joy Behar then introduced BVSD musicians/cast members Renesito Avich and David Oquendo who serenaded Navarro with a birthday song. —Greg Evans, Deadline, 9 Jan. 2026

This alone isn't enough for nuclear fission to sustain itself, but at Oklo, groundwater that flowed through these rocks acted as a natural neutron moderator – similarly to how water is used in many of today's reactors. —New Atlas, 8 Jan. 2026

Word History

First Known Use

circa 1560, in the meaning defined at sense 2

Rhymes for moderator

• activator
• actuator
• agitator
• alligator
• allocator
• alternator
• animator
• annotator
• applicator
• arbitrator
• aspirator
• aviator

Kids Definition

moderator

noun

mod·​er·​a·​tor ˈmäd-ə-ˌrāt-ər 

1

: one that moderates: as

a

: the leader of a Presbyterian governing body

b

: the chairperson of a town meeting

c

: the chairperson of a discussion group (as on television)

2

: a substance (as graphite) used for slowing down neutrons in a nuclear reactor

Medical Definition

moderator

noun

mod·​er·​a·​tor ˈmäd-ə-ˌrāt-ər 

: a substance (as graphite, deuterium in heavy water, or beryllium) used for slowing down neutrons in a nuclear reactor