modishness vs last word

modishness and last word both are nouns.

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

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

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

modishness (noun)	last word (noun)
elegance by virtue of being fashionable	elegance by virtue of being fashionable
	the final statement in a verbal argument
	an authoritative statement