incident vs peripheral

incident and peripheral both are nouns.

Word	Noun	Adjective	Verb	Adverb
incident	Yes	Yes	No	No
peripheral	Yes	Yes	No	No

incident (noun)	peripheral (noun)
a single distinct event	electronic equipment external to the circuit board that contains the CPU of a computer
a public disturbance

incident (adjective)	peripheral (adjective)
(sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence	on or near an edge or constituting an outer boundary; the outer area
falling or striking of light rays on something	related to the key issue but not of central importance