back channel

n.an alternative to the regular channels of communication that is used when agreements must be made secretly (especially in diplomacy or government)

adj.via a back channel

同义词：back-channel

Prosodic features which cue back-channel responses in English and Japanese ☆
Tsukahara, W.: Prosodic features which cue back-channel responses in english and japanese. Journal of Pragmatics 23, 1177-1207
Wireless back channel for satellite television system
Multi-participant conference system with controllable content delivery using a client monitor back-channel
On back-channel behavior in Japanese and English casual conversation
Local video loopback method for a multi-participant conference system using a back-channel video interface
The role of audible and visible back-channel responses in interpersonal communication.
Threshold Voltage Control of Amorphous Gallium Indium Zinc Oxide TFTs by Suppressing Back-Channel Current
High performance indium-zinc-oxide thin-film transistors fabricated with a back-channel-etch-technique
Fluid Semantic Back-Channel Feedback in Dialogue: Challenges and Progress