sex activity vs fearful

sex activity is a noun but fearful is not a noun.

Word	Noun	Adjective	Verb	Adverb
sex activity	Yes	No	No	No
fearful	No	Yes	No	No

sex activity (noun)	fearful (noun)
activities associated with sexual intercourse

sex activity (adjective)	fearful (adjective)
	lacking courage; ignobly timid and faint-hearted
	experiencing or showing fear
	causing fear or dread or terror
	extremely distressing
	timid by nature or revealing timidity