unsure vs shy

unsure is not a noun while shy is a noun.

Word	Noun	Adjective	Verb	Adverb
unsure	No	Yes	No	No
shy	Yes	Yes	Yes	No

As adjectives, unsure and shy are synonyms defined as:

Other synonyms of unsure include diffident, timid.

unsure (noun)	shy (noun)
	a quick throw

unsure (adjective)	shy (adjective)
lacking or indicating lack of confidence or assurance	lacking self-confidence
lacking self-confidence	short
	wary and distrustful; disposed to avoid persons or things

unsure (verb)	shy (verb)
	throw quickly
	start suddenly, as from fright