serious vs intellectual

serious is not a noun while intellectual is a noun.

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

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

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