- noun a peripheral such as a terminal in a workstation that can be used for both inputting and outputting data to a processor
- Abbreviation of input/output device. Any peripheral which transfers data to a CPU and/or receives data from a CPU. Such devices include keyboards, pointing devices, digitizing tablets, scanners, disk drives, microphones, monitors, printers, and speakers. Also, any external device which otherwise assists, enhances, or depends on computer function. Also called I/O unit, or peripheral (1).