direful vs frightening

direful is not a noun while frightening is a noun.

Word	Noun	Adjective	Verb	Adverb
direful	No	Yes	No	No
frightening	Yes	Yes	No	No

As adjectives, direful and frightening are synonyms defined as:

Other synonyms of direful include awful, dire, dread, dreaded, dreadful, fearful, fearsome, horrendous, horrific, terrible.

direful (noun)	frightening (noun)
	the act of inspiring with fear

direful (adjective)	frightening (adjective)
causing fear or dread or terror	causing fear or dread or terror