fortuity vs happening

fortuity and happening both are nouns.

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

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

fortuity: anything that happens suddenly or by chance without an apparent cause
happening: an event that happens

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

fortuity (noun)	happening (noun)
anything that happens suddenly or by chance without an apparent cause	an event that happens