A
mean,
petty, shrewish, malicious person, typically
female (though in rare cases a "cunt" can be male); commonly considered the pinnacle of derogatory and pejorative expressions.
"Sharon is a total cunt." This is typical usage which describes a
female who is simply "beyond bitch".
"Fred is a fucking cunt." This is an example of one of those rare
male usages; not only is Fred "beyond bitch" in this case, but he is also worthy of emascualtion (sometimes referred to as a "
punt" -- a "pussy" and a "cunt" combined).