(computer science) an electronic device that must be attached to a computer in order for it to use protected software
"I can't install the new game until I find my USB dongle, since the developer requires it to run their protected software."
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.
"I had to buy a cheap USB dongle so my old laptop could finally connect to the new Wi-Fi network at work."