intellectual vs serious

intellectual is a noun but serious is not a noun.

Word	Noun	Adjective	Verb	Adverb
intellectual	Yes	Yes	No	No
serious	No	Yes	No	No

intellectual (noun)	serious (noun)
a person who uses the mind creatively

intellectual (adjective)	serious (adjective)
appealing to or using the intellect	concerned with work or important matters rather than play or trivialities
involving intelligence rather than emotions or instinct	completely lacking in playfulness
of or associated with or requiring the use of the mind	causing fear or anxiety by threatening great harm
	requiring effort or concentration; complex and not easy to answer or solve
	of great consequence
	appealing to the mind