optimistic vs positive

optimistic is not a noun while positive is a noun.

Word	Noun	Adjective	Verb	Adverb
optimistic	No	Yes	No	No
positive	Yes	Yes	No	No

optimistic (noun)	positive (noun)
	a film showing a photographic image whose tones correspond to those of the original subject
	the primary form of an adjective or adverb; denotes a quality without qualification, comparison, or relation to increase or diminution

optimistic (adjective)	positive (adjective)
expecting the best in this best of all possible worlds	characterized by or displaying affirmation or acceptance or certainty etc.
expecting the best	indicating existence or presence of a suspected condition or pathogen
	reckoned, situated or tending in the direction which naturally or arbitrarily is taken to indicate increase or progress or onward motion
	of or relating to positivism
	involving advantage or good
	persuaded of; very sure
	having a positive charge
	marked by excessive confidence
	formally laid down or imposed
	greater than zero
	impossible to deny or disprove