From Trisia [Care to explain that?} Yes, there are two explanations. First, incivility together with undutifulness and others are in the English language because the language borrows everythinig. More important, you might think that words like those remain on the books because of the thesdaurus which is untrue. The truth is, those vicious people who compose cross-word puzzles need words like incivility and undutifulness.
Now you know the truth.
I disagree. Although disrespect is to some extent synonymous with incivility, I don't think the meaning is exactly the same. One of the joys of English is the capacity to express very precise meanings; banning words would limit our capacity for expression (see Orwell's "1984").
My understanding is that the prefix un- usually goes with verbs or adjectives to describe the opposite of somthing, a reversal - barbaric. The prefix in- usually means a lack of somthing or some quality - without. So incivility seems "correct" not incivil - you don't lack civil (adjective) you lack civility (noun). But what the hell we understand and thats the great thing about language. And as far as banning words - please - will not work.