socket
Incabling, a coupling is an intermediate piece with which two identical connectors are connected together.
Couplings are required for the detachable connection of two cables, at the ends of which there are identical plugs, but no socket. Couplings have their transmission parameters and must harmonize with those of the plugs and the connected high- frequency cables, especially in high-frequency applications. For example, a 50-ohm cable must not be connected to a 75-ohm coupling, as this will cause reflection.