assurance vs incertain

assurance is a noun but incertain is not a noun.

Word	Noun	Adjective	Verb	Adverb
assurance	Yes	No	No	No
incertain	No	Yes	No	No

assurance (noun)	incertain (noun)
freedom from doubt; belief in yourself and your abilities
a statement intended to inspire confidence
a binding commitment to do or give or refrain from something
a British term for some kinds of insurance

assurance (adjective)	incertain (adjective)
	lacking or indicating lack of confidence or assurance