fun vs impertinence

fun and impertinence both are nouns.

Word	Noun	Adjective	Verb	Adverb
fun	Yes	No	No	No
impertinence	Yes	No	No	No

As nouns, impertinence is a hyponym of fun; that is, impertinence is a word with a more specific, narrower meaning than fun:

fun (noun)	impertinence (noun)
activities that are enjoyable or amusing	inappropriate playfulness
violent and excited activity	the trait of being rude and impertinent; inclined to take liberties
a disposition to find (or make) causes for amusement	an impudent statement
verbal wit or mockery (often at another's expense but not to be taken seriously)