Two-way communication between means that information is flowing in both directions between two parties.

In journalism, a two-way is an informal style of reporting that involves a conversation between two people. The most common arrangement is for a reporter in the field to talk to the host of a news program. The two usually conduct the conversation as if this were the first time the information was being disclosed to the host. While this may be true for breaking news, more often the host has been briefed in advance about what information the reporter has to share, so that the host can ask questions which the reporter can easily and naturally answer.

Ménage à trois (sexual meaning of "three-way")

Two-way street