名詞 moderator:

1. any substance used to slow down neutrons in nuclear reactors
2. in the Presbyterian church, the officer who presides over a synod or general assembly
3. someone who presides over a forum or debate
4. someone who mediates disputes and attempts to avoid violence

mod.er.a.tor

n.（名詞）
One that moderates, as:
仲裁的人
One that arbitrates or mediates.
公斷人或調解人
One who presides over a meeting, forum, or debate.
主持人：主持會議，論壇或討論會的人
The officer who presides over a synod or general assembly of the Presbyterian Church.
主持官員：主持基督教長老會的會議或大會的官員
Physics A substance, such as water or graphite, that is used in a nuclear reactor to decrease the speed of fast neutrons and increase the likelihood of fission.
【物理學】 慢化劑：一種物質，如水或石墨在核反應堆中用來減緩中子運動速度和提高裂變可能性的物質