n.

1. 仲裁者
2. 会议主席；（电视等）节目主持人
3. 调节器；【物】减速材料
4. 【英】主考人；监考人

n.

1. an arbitrator or mediator.
   ▸a presiding officer, especially a chairman of a debate.
   ▸a Presbyterian minister presiding over an ecclesiastical body.
2. Brit. a person who moderates examination papers.
3. Physics  a substance used in a nuclear reactor to retard neutrons.
4. a person who moderates an Internet bulletin board or chat room.