impudent vs smart

impudent is not a noun while smart is a noun.

Word	Noun	Adjective	Verb	Adverb
impudent	No	Yes	No	No
smart	Yes	Yes	Yes	No

As adjectives, impudent and smart are synonyms defined as:

Other synonyms of impudent include fresh, impertinent, overbold, sassy, saucy, wise.

impudent (noun)	smart (noun)
	a kind of pain such as that caused by a wound or a burn or a sore

impudent (adjective)	smart (adjective)
marked by casual disrespect	showing mental alertness and calculation and resourcefulness
improperly forward or bold	capable of independent and apparently intelligent action
	quick and brisk
	improperly forward or bold
	characterized by quickness and ease in learning
	painfully severe
	elegant and stylish

impudent (verb)	smart (verb)
	be the source of pain