happy-go-lucky vs harum-scarum

happy-go-lucky is not a noun while harum-scarum is a noun.

Word	Noun	Adjective	Verb	Adverb
happy-go-lucky	No	Yes	No	No
harum-scarum	Yes	Yes	No	Yes

As adjectives, happy-go-lucky and harum-scarum are synonyms defined as:

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

happy-go-lucky (noun)	harum-scarum (noun)
	a reckless impetuous irresponsible person

happy-go-lucky (adjective)	harum-scarum (adjective)
cheerfully irresponsible	cheerfully irresponsible

happy-go-lucky (adverb)	harum-scarum (adverb)
	in a wild or reckless manner