peripheral

(noun) (computer science) electronic equipment connected by cable to the CPU of a computer. Synonyms: computer peripheral, peripheral device. Examples: "Disk drives and printers are important peripherals."

(adj) on or near an edge or constituting an outer boundary; the outer area. Synonyms: peripheral (vs. central). Examples: "Russia's peripheral provinces." "Peripheral suburbs."

(adj) related to the key issue but not of central importance. Examples: "A peripheral interest." "Energy is far from a peripheral issue in the economy." "Peripheral issues."