frighten off vs scare

frighten off is not a noun while scare is a noun.

Word	Noun	Adjective	Verb	Adverb
frighten off	No	No	Yes	No
scare	Yes	No	Yes	No

As verbs, frighten off and scare are synonyms defined as:

frighten off and scare: cause to lose courage; to be daunted; to be scared away

Other synonyms of frighten off include dash, daunt, frighten away, pall, scare away, scare off.

frighten off (noun)	scare (noun)
	a sudden attack of fear
	sudden mass fear and anxiety over anticipated events

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