A dongle is a small hardware device that plugs into a computer or mobile device to provide additional functionality. Synonyms for the word "dongle" include adapter, connector, attachment, and extension cord. An adapter is a device that connects to another device and converts the signals or power from one type to another. A connector is a device that physically links two components, facilitating communication between them. An attachment is a device that can be added to something else to provide additional functionality. An extension cord is a cable that extends the reach of a power supply, allowing it to be used over a greater distance. All of these synonyms have a similar purpose to a dongle and may be used interchangeably to describe a small hardware device that enhances the functionality of a computer or mobile device.