incident vs happening

incident and happening both are nouns.

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

As nouns, happening is a hypernym of incident; that is, happening is a word with a broader meaning than incident:

Other hypernyms of incident include natural event, occurrence, occurrent.

incident (noun)	happening (noun)
a single distinct event	an event that happens
a public disturbance

incident (adjective)	happening (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