harum-scarum vs carefree

harum-scarum is a noun but carefree is not a noun.

Word	Noun	Adjective	Verb	Adverb
harum-scarum	Yes	Yes	No	Yes
carefree	No	Yes	No	No

As adjectives, harum-scarum and carefree are synonyms defined as:

Other synonyms of harum-scarum include devil-may-care, freewheeling, happy-go-lucky, slaphappy.

harum-scarum (noun)	carefree (noun)
a reckless impetuous irresponsible person

harum-scarum (adjective)	carefree (adjective)
cheerfully irresponsible	cheerfully irresponsible
	free of trouble and worry and care

harum-scarum (adverb)	carefree (adverb)
in a wild or reckless manner