The correct pairings are either … or and neither … nor. It is wrong and sloppy to say neither … or. This is such a simple rule, one that everyone learns early in elementary school. Why, then, do so many journalists and other professional writers routinely violate it? And why do presumably intelligent editors tolerate the error?
Here’s an irritating example from Huffington Post that just happened to catch my eye this afternoon: “Romney’s defense of his action is that he did something neither illegal or unusual.” The use of or instead of nor in this sentence is the sort of mistake that casts doubt on the author’s conscientiousness and sophistication.