dongle

1. (computer hardware) Any small device that plugs into an electronic device, typically a computer, and alters its functionality. Common examples include wireless modems, digital media players, software copy protect devices, and adapters.Examples: "FreedomPop will offer three different flavors of broadband: a USB dongle that allows you to connect your computer to the internet, a WiFi hotspot device, and an iPhone case that allows you to override the phone's existing network and use it as a FreedomPop hotspot."

2. (computer hardware) A hardware device used by a specific application for purposes of copy protection.Examples: "Take the dongle, for example. It is the summit of copy protection, an explicit melding of software and hardware. Without the right hardware key—the dongle—plugged into the machine's parallel port, the software won't run."