defeated vs disappointed

defeated is a noun but disappointed is not a noun.

Word	Noun	Adjective	Verb	Adverb
defeated	Yes	Yes	No	No
disappointed	No	Yes	No	No

As adjectives, defeated and disappointed are synonyms defined as:

Other synonyms of defeated include discomfited, foiled, frustrated, thwarted.

defeated (noun)	disappointed (noun)
people who are defeated

defeated (adjective)	disappointed (adjective)
beaten or overcome; not victorious	disappointingly unsuccessful
disappointingly unsuccessful