Other forms: peripherals
A peripheral is any device plugged in around the main machine. Connect a peripheral, USB peripherals, peripheral devices.
Keyboards, mice, printers and drives are peripherals — anything that is not the computer itself. As an adjective it means at the edge and so of secondary importance: a peripheral issue, peripheral to the argument. Peripheral vision is what you see at the edges without looking, which is better at detecting movement than the centre is. Note periphery.
1nounperipheralA device plugged in around the main machine.
“The printer, scanner and other peripherals are connected to the computer by cables.”
2adjectiveedgeAt the edge and so of secondary importance.
“Let's focus on the main problem and leave the peripheral details for later.”
peripheral is a device or an edge position.
Middle French
peripherie
English
periphery
English, today
peripheral
From periphery + -al. periphery Borrowed from Middle French peripherie. Middle French peripherie. Compare Middle English periferie (“one of three layers of atmosphere (lower, middle, and upper) believed to surround the Earth”), from the same origin, although the Modern English term most likely does not descend from it.
Etymology from Wiktionary, CC BY-SA