happenstance vs fortuity

happenstance and fortuity both are nouns.

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

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

happenstance: an event that might have been arranged although it was really accidental
fortuity: anything that happens suddenly or by chance without an apparent cause

Other hypernyms of happenstance include accident, chance event, stroke.

happenstance (noun)	fortuity (noun)
an event that might have been arranged although it was really accidental	anything that happens suddenly or by chance without an apparent cause