cardboard vs unreal

cardboard is a noun but unreal is not a noun.

Word	Noun	Adjective	Verb	Adverb
cardboard	Yes	Yes	No	No
unreal	No	Yes	No	No

cardboard (noun)	unreal (noun)
a stiff moderately thick paper

cardboard (adjective)	unreal (adjective)
without substance	lacking in reality or substance or genuineness; not corresponding to acknowledged facts or criteria
	not actually such; being or seeming fanciful or imaginary
	lacking material form or substance; unreal
	contrived by art rather than nature