I. pe ‧ riph ‧ e ‧ ral 1 /pəˈrɪf ə rəl/ BrE AmE adjective
1 . formal not as important as other things or people in a particular activity, idea, or situation:
a diplomat who had a peripheral role in the negotiations
Her involvement in the case was peripheral.
peripheral to
The romance is peripheral to the main plot of the movie.
2 . formal in the outer area of something, or relating to this area:
the city’s peripheral suburbs
the peripheral nervous system
3 . peripheral vision your ability to see things to the side of you when you look straight ahead
4 . technical peripheral equipment can be connected to a computer and used with it
—peripherally adverb
II. peripheral 2 BrE AmE noun [countable] technical
a piece of equipment that is connected to a computer and used with it, for example a ↑ printer