chairman; moderator; toastmaster; master of ceremonies; chairperson; host (of a TV show, etc.)
司会者が登壇者を紹介した。
The host introduced the speakers on stage.
司会者の進行で会議がスムーズに進んだ。
The meeting proceeded smoothly under the moderator's guidance.
その司会者はユーモアのある話し方で観客を引き付ける。
That host draws in the audience with his humorous way of speaking.