I. pə-ˈri-f(ə-)rəl adjective
Date: 1808
1. : of, relating to, involving, or forming a periphery or surface part
2.
a. : of, relating to, affecting, or being part of the peripheral nervous system
peripheral nerves
peripheral neuritis
b. : of, relating to, or being blood in the systemic circulation
peripheral lymphocytes
3. : of, relating to, or being the outer part of the field of vision
good peripheral vision
4. : auxiliary , supplementary
peripheral equipment
also : of or relating to computer peripherals
• pe·riph·er·al·ly adverb
II. noun
Date: 1966
: a device connected to a computer to provide communication (as input and output) or auxiliary functions (as additional storage)