fearfulness vs scare

fearfulness and scare both are nouns.

Word	Noun	Adjective	Verb	Adverb
fearfulness	Yes	No	No	No
scare	Yes	No	Yes	No

As nouns, scare is a hyponym of fearfulness; that is, scare is a word with a more specific, narrower meaning than fearfulness:

fearfulness: an emotion experienced in anticipation of some specific pain or danger (usually accompanied by a desire to flee or fight)
scare: a sudden attack of fear

fearfulness (noun)	scare (noun)
the trait of being afraid	a sudden attack of fear
an emotion experienced in anticipation of some specific pain or danger (usually accompanied by a desire to flee or fight)	sudden mass fear and anxiety over anticipated events

fearfulness (verb)	scare (verb)
	cause fear in
	cause to lose courage; to be daunted; to be scared away