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

“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

Traditional CAR-NK approaches usually depend on mature NK cells collected from sources such as peripheral blood or cord blood.

From Science Daily • Feb. 17, 2026

"It is more a peripheral vision or spatial awareness thing, sensing that something isn't quite right in the defence or there is more space than there should be."

From BBC • Feb. 11, 2026

For decades, U.S. macroeconomic debates treated regulation as a sideshow—important for lawyers, lobbyists, and compliance officers but peripheral to the “real” drivers of economic performance, such as interest rates, deficits, and stimulus.

From Barron's • Feb. 2, 2026

In my peripheral vision, the same still image of Tariq flashes, over and over.

From "How It Went Down" by Kekla Magoon

Related Words

• incidental
• tangential