smartness vs last word

smartness and last word both are nouns.

Word	Noun	Adjective	Verb	Adverb
smartness	Yes	No	No	No
last word	Yes	No	No	No

As nouns, smartness and last word are synonyms defined as:

Other synonyms of smartness include chic, chichi, chicness, modishness, stylishness, swank.

smartness (noun)	last word (noun)
elegance by virtue of being fashionable	elegance by virtue of being fashionable
liveliness and eagerness	the final statement in a verbal argument
intelligence as manifested in being quick and witty	an authoritative statement
a kind of pain such as that caused by a wound or a burn or a sore