slap-up vs swell

slap-up is not a noun while swell is a noun.

Word	Noun	Adjective	Verb	Adverb
slap-up	No	Yes	No	No
swell	Yes	Yes	Yes	No

As adjectives, slap-up and swell are synonyms defined as:

Other synonyms of slap-up include bang-up, bully, corking, cracking, dandy, great, groovy, keen, neat, nifty, not bad, old, peachy, smashing.

slap-up (noun)	swell (noun)
	a crescendo followed by a decrescendo
	the undulating movement of the surface of the open sea
	a rounded elevation (especially one on an ocean floor)
	a man who is much concerned with his dress and appearance

slap-up (adjective)	swell (adjective)
excellent	excellent

slap-up (verb)	swell (verb)
	expand abnormally
	cause to become swollen
	increase in size, magnitude, number, or intensity
	come up, as of a liquid
	become filled with pride, arrogance, or anger
	come up (as of feelings and thoughts, or other ephemeral things)