intermediary
noun [ C ] uk/ˌɪn.təˈmiː.di.ə.ri/ us/ˌɪn.t̬ɚˈmiː.di.ə.ri/
调解人，中间人
someone who carries messages between people who are unwilling or unable to meet
The police negotiated with the gunman through an intermediary. 警方通过调解人与持枪歹徒谈判。
The former president has agreed to act as an intermediary between the government and the rebels. 前总统已经同意在政府和叛军之间充当调解人。
Synonym: go-between