from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A hardware device that serves as copy protection for certain software by rendering the software inoperable when the device is not plugged into a printer port.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. Any small device which plugs into an electronic device, typically a computer, and alters its functionality. Common examples include wireless modems, software copy protect devices, and adapters. Some USB keyboards and mice include USB to PS/2 adapter dongles, enabling their use on machines with PS/2 ports.
- n. A hardware device utilized by a specific application for purposes of copy protection.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. (computer science) an electronic device that must be attached to a computer in order for it to use protected software
Probably arbitrary coinage.(American Heritage® Dictionary of the English Language, Fourth Edition)
Apparently from dangle. (Wiktionary)