peripheral

/pəˈrɪfərəl/

/pəˈrɪfərəl/

Other forms: peripherals

Scanners, printers, and speakers are peripheral devices for a computer because they aren't central to the working of the computer itself. Anything peripheral is on the margin, or outside, while main things, like a computer's processor, are not peripheral.

Outside of computer jargon, peripheral is a common term in eye exams, which measure peripheral vision to see how far toward the outer right and left edges you can see. Peripheral also describes nerves from the body's peripheral system, which are secondary to the main system but branch off of it — like the wires between peripheral devices and a computer.

Definitions of peripheral

1. adjective

   on or near an edge or constituting an outer boundary; the outer area
   “Russia's peripheral provinces”

   “peripheral suburbs”

   synonyms:

   circumferential

   lying around or just outside the edges or outskirts

   fringy, marginal

   at or constituting a border or edge

   encircling, skirting

   being all around the edges; enclosing

   off-base

   located outside a military base

   antonyms:

   central

   in or near a center or constituting a center; the inner area

   amidship

   located in the middle part of a ship or aircraft

   bicentric

   having two centers

   bifocal

   having two foci

   center, halfway, middle, midway

   equally distant from the extremes

   centered

   being or placed in the center

   centric, centrical

   having or situated at or near a center

   focal, nodal

   having or localized centrally at a focus

   medial, median

   relating to or situated in or extending toward the middle

   middlemost, midmost

   being in the exact middle

   nuclear

   constituting or like a nucleus
2. adjective

   related to the key issue but not of central importance
   “a peripheral interest”

   “energy is far from a peripheral issue in the economy”

   “peripheral issues”

   synonyms:

   incident, incidental

   (sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence
3. noun

   (computer science) electronic equipment connected by cable to the CPU of a computer
   “disk drives and printers are important peripherals”

   synonyms: computer peripheral, peripheral device

   types:

   data input device, input device

   a device that can be used to insert data into a computer or other computational device

   output device

   electronic or electromechanical equipment connected to a computer and used to transfer data out of the computer in the form of text, images, sounds, or other media

   printer

   (computer science) an output device that prints the results of data processing

   computer keyboard, keypad

   a keyboard that is a data input device for computers; arrangement of keys is modelled after the typewriter keyboard

   dot matrix printer, dot printer, matrix printer

   a printer that represents each character as a pattern of dots from a dot matrix

   joystick

   a manual control consisting of a vertical handle that can move freely in two directions; used as an input device to computers or to devices controlled by computers

   digital scanner, image scanner, scanner

   an electronic device that generates a digital representation of an image for data input to a computer

   type of:

   electronic equipment, electronics

   equipment that involves the controlled conduction of electrons (especially in a gas or vacuum or semiconductor)