Dongle

A dongle is a small piece of hardware that attaches to computer, TV, or other electronic device, and that when attached enables additional functions such as copy protection, audio, video, games, data, or other services. These services are available only when the dongle is attached.

Although, the term "dongle" was originally used to refer only to software protection dongles, it is now more commonly used to refer to very short cables that connect relatively large jacks to smaller plugs, allowing cables to be easily removed and replaced from computing devices with limited available surface space.