optimism vs disposition

optimism and disposition both are nouns.

Word	Noun	Adjective	Verb	Adverb
optimism	Yes	No	No	No
disposition	Yes	No	No	No

As nouns, disposition is a hypernym of optimism; that is, disposition is a word with a broader meaning than optimism:

Other hypernyms of optimism include temperament.

optimism (noun)	disposition (noun)
a general disposition to expect the best in all things	the act or means of getting rid of something
the optimistic feeling that all is going to turn out well	your usual mood
	a natural or acquired habit or characteristic tendency in a person or thing
	an attitude of mind especially one that favors one alternative over others