peripheral
pe-riph-er-al
adjective
Relating to the outer edge or less important part of something.
"Keep an eye on your peripheral vision."
noun
An external device connected to a computer, such as a printer or mouse.
"My new printer is a useful peripheral."
Thesaurus
Synonyms: incident, incidental, computer peripheral, peripheral device, off-base, marginal, circumferential, skirting, encircling, fringy
Antonyms: central