intermediary

The real estate agent acted as an intermediary between the buyer and the seller to finalize the price.

(Chinese) 房地产经纪人在买卖双方之间充当中间人，以确定最终价格。

Since the two countries had no diplomatic ties, a neutral nation served as an intermediary.

(Chinese) 由于两国没有外交关系，一个中立国家充当了中间人的角色。