half duplex

This term is primarily used in telecommunications and networking to describe a specific operational mode. It is most commonly associated with walkie-talkies or early Ethernet hubs, where the user must wait for the other party to finish transmitting before they can respond. This creates a "push-to-talk" dynamic, contrasting with full duplex systems like telephone calls where both parties can speak and hear at the same time.

In a technical context, the term is used both as a modifier for hardware (e.g., a half duplex link) and as a noun describing the state of the connection. Because it refers to a specific technical standard or mode of operation, it is typically treated as an uncountable noun when referring to the concept of the communication mode itself.