devil-may-care vs slaphappy

devil-may-care and slaphappy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
devil-may-care	No	Yes	No	No
slaphappy	No	Yes	No	No

As adjectives, devil-may-care and slaphappy are synonyms defined as:

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

devil-may-care (adjective)	slaphappy (adjective)
cheerfully irresponsible	dazed from or as if from repeated blows
marked by a carefree unconventionality or disreputableness	cheerfully irresponsible