backchannel
noun [ C ] uk/ˈbækˌtʃæn.əl/ us/ˈbækˌtʃæn.əl/
（传递消息或进行交流的）秘密渠道，特殊途径
a method of communication or discussion that is not direct or made public
They were accused of paying a businessman to act as a secret backchannel to top officials. 他们被指控付钱给一名商人，让他充当与高层官员的秘密联络渠道。
backchannel
verb (also back-channel) uk/ˈbækˌtʃæn.əl/ us/ˈbækˌtʃæn.əl/ -ll- or -l-
[ I or T ]（通过秘密渠道或特殊途径）进行交流
to communicate or take part in discussions in a way that is not direct or made public
He was asked about his role in backchannelling between the two governments. 有人问他在两国政府私下交流的过程中起到了什么作用。