incidence vs incident

incidence and incident both are nouns.

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

incidence (noun)	incident (noun)
the striking of a light beam on a surface	a single distinct event
the relative frequency of occurrence of something	a public disturbance

incidence (adjective)	incident (adjective)
	(sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence
	falling or striking of light rays on something