smart vs impudent

smart is a noun but impudent is not a noun.

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

As adjectives, smart and impudent are synonyms defined as:

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

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

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

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