n.

1. 仲裁者
2. 會議主席；（電視等）節目主持人
3. 調節器；【物】減速材料
4. 【英】主考人；監考人

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.