event vs nonevent

event and nonevent both are nouns.

Word	Noun	Adjective	Verb	Adverb
event	Yes	No	No	No
nonevent	Yes	No	No	No

As nouns, nonevent is a hyponym of event; that is, nonevent is a word with a more specific, narrower meaning than event:

event: something that happens at a given place and time
nonevent: an anticipated event that turns out to be far less significant than was expected

event (noun)	nonevent (noun)
something that happens at a given place and time	an anticipated event that turns out to be far less significant than was expected
a phenomenon located at a single point in space-time; the fundamental observational entity in relativity theory
a phenomenon that follows and is caused by some previous phenomenon
a special set of circumstances