nonoccurrence vs absence

nonoccurrence and absence both are nouns.

Word	Noun	Adjective	Verb	Adverb
nonoccurrence	Yes	No	No	No
absence	Yes	No	No	No

As nouns, absence is a hypernym of nonoccurrence; that is, absence is a word with a broader meaning than nonoccurrence:

nonoccurrence (noun)	absence (noun)
absence by virtue of not occurring	failure to be present
	the state of being absent
	the occurrence of an abrupt, transient loss or impairment of consciousness (which is not subsequently remembered), sometimes with light twitching, fluttering eyelids, etc.; common in petit mal epilepsy
	the time interval during which something or somebody is away