1
formal
: not relating to the main or most important part
If we focus too much on peripheral issues, we will lose sight of the goal.
—often + toHis role in the negotiations was peripheral to the outcome. [=his role in the negotiations was not important in deciding the outcome]
2
computers
: connected to a computer but not an essential part of it
peripheral devices/equipment such as modems and scanners
3
: of or relating to the area that is to the side of the area you are looking at
He saw in his peripheral vision that a car was trying to pass him.
4
medical
: of or relating to the part of the nervous system that is separate from the brain and spinal cord
peripheral nerves
the peripheral nervous system
plural peripherals
computers
: a piece of equipment (such as a printer, speaker, etc.) that is connected to a computer but is not an essential part of it
computer peripherals
Cite this Entry
“Peripheral.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/peripheral. Accessed 2 Nov. 2026.
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