Origin: Latin suffix -al
Peripheral has 5 different meanings across 2 categories:
electronic equipment external to the circuit board that contains the CPU of a computer
"disk drives and printers are important peripherals"
A peripheral device.
"The printer is connected as a peripheral to the computer."
on or near an edge or constituting an outer boundary; the outer area
"Russia's peripheral provinces"
"peripheral suburbs"
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"
On the periphery or boundary.
"The small town lies on the peripheral edge of the vast desert, far from any major cities."
In plain English: Peripheral means being on the edge of something rather than at its center.
"The peripheral vision helped me spot the car approaching from behind without turning my head."
The word peripheral comes from the Latin phrase peripheria, which originally referred to the outer boundary or circumference of a circle. It entered English as an adjective describing anything situated on the edge or outside of a central area.