swell vs slap-up

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

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

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

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

swell (noun)	slap-up (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

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

swell (verb)	slap-up (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)