- a person or thing that adapts
- a contrivance for adapting apparatus to new uses
- a connecting device for parts that would not otherwise fit together
A device that allows one system to connect to and work with another. An adapter may be a simple circuit that converts one set of signals to another; however, the term often refers to devices which are more accurately called "controllers." For example, display adapters (graphics cards) and network adapters (NICs) perform extensive processing. See host adapter and expansion bus.