coupler

中文： 耦合器、车钩、联轴器

1. Anything that serves to couple things together; but especially a device that couples railway carriages.
2. A device that connects two keyboards of an organ together so that they play together.
3. A device used to convert electronic information into audible sound signals for transmission over telephone lines.
4. An electrical device used to transfer energy from one electric device to another, especially without a physical connection.

复数 couplers