peripheral

American  

[puh-rif-er-uhl] / pəˈrɪf ər əl /

adjective

1. relating to, situated in, or constituting the periphery.

   peripheral resistance on the outskirts of the battle area.

2. concerned with relatively minor, irrelevant, or superficial aspects of the subject in question.

3. Anatomy. near the surface or outside of; external.

4. Computers. relating to a device or unit that is separate from but connected to a computer, network host, etc.

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noun

1. Computers.

   1. a device or unit that operates separately from the CPU but is connected to it, such as a mouse, printer, speakers, etc.

   2. a device or unit that is separate from a network’s host computer but in communication with it, such as a shared input terminal, printer, or backup drive.

peripheral British  

/ pəˈrɪfərəl /

adjective

1. not relating to the most important part of something; incidental, minor, or superficial

2. of, relating to, or of the nature of a periphery

3. anatomy of, relating to, or situated near the surface of the body

   a peripheral nerve

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peripheral Scientific  

/ pə-rĭf′ər-əl /

1. Anatomy Relating to or being the surface or outer part of a body or organ.

2. Relating to or being part of the peripheral nervous system.

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1. Computer Science An auxiliary device, such as a printer or modem, distinct from a computer's central processing unit and working memory, and often connected externally.

peripheral Cultural  

1. Any part that is separate from a computer's CPU, such as a printer, a keyboard, or a monitor.

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Other Word Forms

• peripherally
  adverb
• unperipheral
  adjective

Etymology

Origin of peripheral

First recorded in 1800–10; 1965–70 peripheral for def. 4; from Greek peripher(ḗs) ( see periphery ( def. )) + -al ¹ ( def. )

Explanation

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.

Example Sentences

The googly-eyed robots slow down near pedestrians and stop entirely if proximity becomes too close, emit a running sound for audibility, and use 360-degree lights at night to appear in the peripheral vision of humans.

From Los Angeles Times • May 5, 2026

“No other party in the conflict or peripheral to the conflict has been equally vocally confident in the prospect of peace through superior firepower.”

From MarketWatch • Apr. 17, 2026

"We've all had that moment of wandering into a club and scanning the room with your peripheral vision and being like, 'Are they there? Are they there?'" she says.

From BBC • Apr. 2, 2026

The move, first reported by the Financial Times, comes as the artificial intelligence giant seeks to shed what executives have described as peripheral projects as it tries to maintain its lead in the AI market.

From Barron's • Mar. 26, 2026

Still, man, it wasn’t gonna be easy getting past the living room without him catching me in his peripheral.

From "We Were Here" by Matt De La Peña

Related Words

• incidental
• tangential