(n) A repulsive, disgusting, ugly repugnant woman or man. "Un" is the first syllable in unf**kable, unattractive, unbearable, uninteresting, ungrateful and unimportant, but since uns are not worthy of any discussion whatsoever, wasting more than one syllable when describing one is literally a waste of breath.
Uns can achieve "un-ness"by being fat, ugly or unclean, but usually a combination of all 3.
Un are considered by some to be "the third, useless gender" because of their total lack of any sexual attractiveness whatsoever makes them neither male or female.
Rosie O'Donnell can say people dislike her because she's a woman, or because she's a lesbian. But the real reason people dislike her is because she's un. If she looked like Jessica Alba, everyone would love her.