disappointment vs failure

disappointment and failure both are nouns.

Word	Noun	Adjective	Verb	Adverb
disappointment	Yes	No	No	No
failure	Yes	No	No	No

As nouns, failure is a hypernym of disappointment; that is, failure is a word with a broader meaning than disappointment:

disappointment (noun)	failure (noun)
an act (or failure to act) that disappoints someone	an act that fails
a feeling of dissatisfaction that results when your expectations are not realized	an unexpected omission
	an event that does not accomplish its intended purpose
	a person with a record of failing; someone who loses consistently
	lack of success
	loss of ability to function normally
	inability to discharge all your debts as they come due